人教版八年级下学期英语开学测试练习 A卷

这是一份人教版八年级下学期英语开学测试练习 A卷，共18页。试卷主要包含了单选题，完形填空，阅读理解，任务型阅读，根据汉语提示写出单词，书面表达等内容，欢迎下载使用。
人教版八年级下学期英语开学测试
A卷
满分：120分
一、单选题（共15小题；每小题1分，满分15分）
1.—_____ yogurt do you need?
—Three cups.
A. How many  B. How much C. How long  D. How far
2.—Must I come at 6: 30 tomorrow morning?
—No, you needn't. You _____ come one hour later.
A. can  B. need C. should  D. must
3.—Do you know the young man in blue?
—Yes, he is _____ university student and plays _____ part in helping the poor children here.
A. a; a  B. an; a C. a; /  D. an; /
4.We all know that _____ birds fly to Dongting Lake in winter.
A. million  B. millions C. millions of  D. million of
5.The moonlight goes _____ the window and makes the room bright.
A. up  B. across C. down  D. through
6.If you go to the temple fair during the Spring Festival, you _____ many performers showing the traditional art and culture like lion and dragon dances.
A. see  B. saw C. are seeing  D. will see
7.Is there life on other planets? No one can answer the question _____.
A. so far  B. another time C. as far as  D. far from
8.Jack planned _____ his problem of being too fat last year.
A. solving  B. solve C. to solve  D. solved
9.You look the same now as you looked ten years ago. You've _____ changed.
A. completely  B. hardly C. greatly  D. already
10.—How do you like Chinese Poetry Competition on CCTV?
—Wonderful! It's the _____ program I've ever watched.
A. better B. best  C. worse  D. worst
11.After seeing his daughter ________ the school bus, the father left quietly.
A.get on B.get up C.get off D.get away
12.Mother bought a big bottle of milk for me. I only drank half of it just now. The ________ of it ________ in the fridge now.
A.others, are B.rest, is C.rest, are D.other, is
13.When I see an ________ movie, I am always very ________.
A.exciting; exciting B.excited; excited
C.exciting; excited D.excited; exciting
14.—I’m sorry I ________ my homework at home this morning.
—It doesn’t matter. Don’t forget ________ it here tomorrow.
A.left; to take B.forgot; bringing
C.left; to bring D.forgot; to bring
15.—Tom, remember to return this book by Friday.
—_____.
A. Sure, I'd love to  B. That's right C. Got it  D. Sony, I won't
二、完形填空（共10小题；每小题1.5分，满分15分）
After school, everybody left the school and went home except Wang Yong. He was still outside the school gate. His     16     usually came and took him home from school, but today, she was not there. Wang Yong     17     for 20 minutes and then he walked home alone.
    When he got home, he knocked on the door because he did not have the     18    . To his surprise, no one answered the door. Wang Yong thought his mother was in the toilet, so he waited patiently (耐心地). After a few     19    , there was still no answer.
    Wang Yong knocked again, but still no one     20     the door. He didn't know what to do. Just then he heard the     21     voice of his neighbor, Li Ming. Li Ming's mother asked Li Ming to invite Wang Yong to stay in their house. Wang Yong and Li Ming played     22     till evening when Wang Yong's mother came back.
    Wang Yong     23     Li Ming and his mother before he went back to his home. Wang Yong's mother explained that she had a headache and she had to see     24    . From this experience, Wang Yong learned an important lesson, "Neighbors should     25     each other.''
16.A. father  B. neighbor  C. mother  D. teacher
17.A. waited  B. walked  C. ran  D. slept
18.A. book  B. bag  C. ball  D. key
19.A. seconds  B. minutes  C. days  D. weeks
20.A. asked  B. rang  C. answered  D. shouted
21.A. friendly  B. ugly  C. serious  D. low
22.A. sadly  B. happily  C. badly  D. quickly
23.A. touched  B. admired  C. treated  D. thanked
24.A. a doctor  B. an actor  C. a waiter  D. a reporter
25.A. fight  B. know  C. help  D. leave
三、阅读理解（共20小题；每小题2分，满分40分）
   A
Welcome to Happy Toy Store! We have the most popular robot toys! Come here and have a look! You can't miss it!

Name: Nicky
Price: $210
For kids over 7 Nicky can make simple dishes.
It is the most popular robot toy of the year 2018 in our store.

Name: Cow
Price: $195
For kids over 5
It looks like a cow and has four legs. It can move its legs freely (自由地) and dance.

Name: Michael
Price: $220 For kids over 10
It has a big screen on its face. You can use it to learn English online and play games.

Name: Susan
Price: $180
For kids over 8
It is the smallest robot in our store, but it can teach children to speak different languages.
26.The robot Nicky can _____.
A. dance for children B. play games with children
C. cook simple food  D. speak two languages
27.Today is Ben's 6th birthday. His parents can give him the robot _____.
A. Nicky  B. Cow C. Michael  D. Susan
28.What do we know about the robot Michael?
A. Its price is $200. B. It's for the kids at the age of 9.
C. It has a big screen on its back. D. Children can use it to study.
29.The robot Susan is _____ than the other three robots.
A. smaller  B. smarter C. more popular  D. more expensive
30.Sara wants to buy two robot toys, but she only has $380. She can buy _____.
A. Michael and Cow  B. Nicky and Susan
C. Michael and Nicky  D. Susan and Cow
B
Last week a woman and a man came into Jane's travel agency (旅行社) to book a trip for August. When Jane asked where they wanted to go, the woman said she would like to go somewhere warm.
    Jane suggested that they should go to Spain because it is very warm in August. She showed them a picture of a wonderful hotel. The man didn't want to go to Spain, because he didn't like the food there. So Jane suggested Tunisia, and said it is always warm in North Africa. But the woman didn't like it. The next suggestion was Italy. But the woman said she didn't like the weather in Italy.
    When Jane then suggested Greece, the man got a little upset and said no. He thought all hotels in Greece were terrible. His neighbor (邻居) went there and her hotel was only half-built.
    Jane found out that flying to Florida was not a good idea because the woman didn't like being on planes for a long time. After two hours of talking, Jane suggested that they should just stay at home. They thought it was a great idea and left the travel agency.
31.What didn't the man like about Spain?
A. The weather.  B. The food. C. The hotels.  D. The cinemas.
32.What does the underlined word "upset" in Paragraph 3 mean in Chinese?
A.沮丧的  B.愤怒的 C.尴尬的  D.愉快的
33.The man's neighbor stayed at a hotel in Greece. The hotel was _____.
A. small  B. dirty C. half-built  D. dangerous
34.Jane thought Florida was not a good choice because _____.
A. it is too hot there B. the food there is expensive
C. the man didn't have enough time D. the woman didn't like flying for a long time
35.Which is the best title (标题) for the passage?
A. Booking a Trip B. What to Do in August
C. Traveling in Different Countries D. How to Choose the Best Travel Agency
C   
It might be fun to use your smartphone, but be careful. Too much screen time may be harmful to your health.
    First, it is bad for your eyes. A researcher called Sarah Hinkley says the problem comes from the blue light that the screen gives out. Looking at a smartphone for a long time can cause eye strain(劳损), headaches and dry eyes. So it is a good idea to take a break every 15 minutes when you are working at a computer or using a smartphone.
    Second, screen use can do harm to children's brains. A new study shows that using screens too much can affect(影响) how children's brains grow. If children use screens for more than one hour a day, they might have lower levels of white matter in their brains. White matter is a key to the development of language and reading skills. So it is wise to cut down the time of children using all kinds of screens.
    Third, using screens too much will affect your sleep. According to a study, about 95% of the people between the ages of 13 and 64 use electronics before bed, especially the young people under 20. Doctors say that the light from those electronics at night may make you excited before you go to bed. Then it's hard for you to get enough sleep. So you'd better turn off smartphones, TVs, and all other screens an hour before your bedtime.
    To keep healthy, doctors and researchers strongly advise that you shouldn't use screens for long hours.
36.The blue light from your screens can cause _____.
A. eye strain B. headaches C. dry eyes D. all of the above
37.According to the passage, you can't sleep well because you _____.
A. take a break every 15 minutes B. have lower levels of white matter
C. use screens too much before bed D. are the people from 13 to 64
38.Which of the following is NOT true according to the passage?
A. Using smartphones for long hours does harm to your eyes.
B. A lot of screen time affects children's brain growth.
C. The light from electronics at night may make you excited.
D. People of all ages mustn't use electronics.
39.You may read the passage in ______.
A. a science magazine B. a travel diary C. a guide book D. a novel
40.What is the main idea of the passage?
A. The ways to keep healthy. B. The harm of using screens too much.
C. The ways to use screens. D. The advantages of using screens.
D
Did you remember some unforgettable things that happened around you? Have you ever seen a fire? What will you do if there is a fire? Will you shout for help? Or will you just stay there but do nothing? Many people are too afraid to do something when there is a fire. But in fact, this is wrong.
Last Sunday evening my parents went out for a walk with my sister. But I studied alone at home because I would have an English test. Suddenly, I saw bright light in my neighbor’s kitchen. I thought he was cooking so I went on studying.
Soon, there was a terrible smell in the air and I thought something was wrong. I went out and saw fire coming out of my neighbor’s kitchen. So I shouted “Fire! Fire!” But no one heard or came out.
I ran quickly into my house to call 119, and then I rang my neighbor’s doorbell, knocked at the door, but there was no response. I got into the house through the window and found my neighbor sleeping in his bedroom. I woke him up and we rushed out of the house together.
We tried our best to pour water through the kitchen window, but the fire was too heavy. Luckily, the firemen came and put out the fire quickly. When my parents came back, they found I was dirty and tired. After my neighbor told them the whole story, they were happy and said I was a brave boy.
41.The writer didn’t go out for a walk with his parents because ________.
A. his parents only liked his sister
B. he would have an English class
C. he had to study for an English test
D. there was a fire in his neighbor’s kitchen
42.The underlined word “response” can be replaced by ________.
A. result B. answer C. question D. key
43.________ put out the fire at last.
A. The writer B. The writer’s parents
C. The writer’s neighbor D. The firemen
44.According to passage, which of the following is TRUE?
A. The writer’s neighbor was sleeping when the fire started.
B. No one helped the writer’s neighbor put out the fire.
C. The fire happened last Friday evening.
D. The writer’s parents were angry when they knew what had happened.
45.The passage mainly tells ________.
A. how to put out a fire B. my neighbor was a brave man
C. I saved my neighbor from the fire D. I studied for a test at home
四、任务型阅读（共5小题；每小题2分，满分10分）
British band “Duran Duran” is going to be the first pop group to perform online concerts on the online game Second Life.

Second Life is an online 3-dimensional, digital world, which is imagined, created and owned by the players—people all over the world.
It is thought that 370,000 computer game players worldwide have Second Life characters that exist in the Second Life world, on the Internet.
Earlier this year, BBC Radio held music festivals and played an interview from inside the game.
In May of 2006, it held a music festival in Scotland, but also created a festival inside the Second Life game so that people all over the world could take part in their computers.
One of the members of the band, Nick Rhodes, told the BBC News website: “When I first saw Second Life a few months ago, I couldn’t believe my eyes. When I started looking at the people on screen, talking, walking around and doing normal things, I thought this is somewhere between a strange TV show, a strange experience and a video game. I wanted “Duran Duran” to be part of it.” Each band member has a 3-dimensional person and it is hoped they will do their first online concert soon. The audience will be able to join in and react (反应) while the band is on stage.
Rhodes said new technologies like Second Life will become more and more important in the music industry in the future.
The number of people joining the Second Life is growing quickly. Some computer experts said it probably would be the ‘Next Big Thing’ in the future.
46.Is Second Life an online game?

47.What did BBC Radio create inside the Second Life?

48.What was Nick Rhodes’ new idea?

49.How will the band show their first concert online?

50.What does the writer tell us in the last two paragraphs?

五、根据汉语提示写出单词（共5小题；每小题1分，满分5分）
51.I had little time to think about what the _________(未来) held for me.
52.Thank you for your good _________(建议). I can make a better cake now.
53.Please believe yourself! Don’t be _________ (沮丧) all the time。
54.To get better _________ (教育), I decide to go to England in 2016.
55.Most animals have four _______(脚).
六、选择适当的句子补全对话，其中有两项为多余项（共5小题；每小题2分，满分10分）。
A: Hey, Steve.
B: Hi! How’s it going recently?
A: Terrible! I always feel upset.
B: 56 _________
A: My parents always wish me to study hard and always compare me with others. It makes me stressed out. 57 _________
B: Don’t worry. Why don’t you chat on the Internet to share your feelings with others?
A: Really? 58 ________
B: Sure. It’s very popular among us young people. You can also get many replies from friends.
A: 59 _________
B: Well, you should have a try first. If you have a chance, you should invite them to read your micro blog (微博). They’ll know you better.
A: 60 ________ Thank you.
A.But what if my parents don’t let me do it?
B.That sounds great.
C.What happened to you?
D.Is it helpful to me?
E.I don’t know how to deal with it.
F.It’s so embarrassing.
G.I won’t do it.
七、书面表达（共1小题；满分25分）
假设你是学校环保社团的负责人，你号召全体成员参加“地球一小时”活动，保护地球。请根据以下要点提示，完成一篇保护地球的发言稿。
地球的重要性
1. 地球是我们美丽的家，有森林、河流等，也有不同的动植物；
2. 地球为我们提供了空气、水和食物。
如何保护地球
1. 参与“地球一小时”活动，熄灯一小时；
2. 停止随地丢垃圾；
3. ……（补充至少一点）
号召大家保护地球
要求：
1. 必须包含以上提示内容，可适当发挥。
2. 条理清晰、行文连贯、标点正确、书面整洁。
3. 文中不得出现真实姓名和学校。
4. 80词左右。开头已给出，不计入总词数。
参考词汇：地球一小时 Earth Hour
Dear students,
It is my great honor to speak here. Today, I am going to talk about how to protect the Earth. ____________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________




答案以及解析
一、
1.答案：B
解析：由答语可知,问句提问数量; yogurt是不可数名词。故选B项。
2.答案：A
解析：can意为“能; 可以”; need意为“需要”; should意为“应该”; must意为“必须”。根据语境可知应选A项。
3.答案：A
解析：university是发音以辅音音素开头的名词,且此处是泛指,所以用不定冠词a; play a part in doing sth.意为“在做某事中发挥作用”,是固定结构。故选A项。
4.答案：C
解析：millions of…意为“数百万的……”,符合语境。故选C项。
5.答案：D
解析：句意为:月光透过窗户,使房间变得明亮。根据语境可知,月光是从窗户穿过,through表示从物体内部穿过,符合语境。故选D项。
6.答案：D
解析：此句含有If引导的条件状语从句,从句用一般现在时,主句用一般将来时。故选D项。
7.答案：A
解析：so far意为“迄今为止”; another tine意为“下次”; as far as意为“远至; 据……”; far from意为“远离”。根据语境可知应选择A项。
8.答案：C
解析：句意为:杰克去年计划解决他过于肥胖的问题。plan to do sth.意为“计划做某事”,为固定用法,故选C项。
9.答案：B
解析：completely意为“完全地”; hardly意为“几乎不”; greatly意为“大大地”; already意为“已经”。结合语境,故选B项。
10.答案：B
解析：根据语境及空前的the可知,此处应用best,表示“最棒的”。故选B项。
11.答案：A
解析：句意：看到女儿上了校车，父亲悄悄地离开了。考查动词短语。get on上车；get up起床；get off下车；get away走开。根据“the father left quietly”可知，父亲应该是在看到女儿上了校车之后安静地走开，故选A。
12.答案：B
解析：句意：妈妈给我买了一大瓶牛奶。我刚才只喝了一半。剩下的都在冰箱里了。考查主谓一致。others其他的人或物；rest剩余部分；other其他的。根据“I only drank half of it just now.”可知此处指剩余的牛奶，用the rest of it，谓语与it保持一致，用is。故选B。
13.答案：C
解析：句意：当我看到一部激动人心的电影时, 我总是很兴奋。考查形容词辨析。exciting令人兴奋的, 形容物；excited兴奋的, 形容人。空格一处修饰名词movie用exciting；空格二处形容人, 用形容词excited。故选C。
14.答案：C
解析：句意：—对不起, 今天早上我把作业忘在家里了。—没关系。别忘了明天把它带来。考查动词辨析和非谓语。left落, 离开；forgot忘记；bring带来；take带去。第一空表示“把作业落在家里了”, forget后不能加地点, 所以第一空用leave, 排除BD；第二空表示“不要忘记把作业带过来”, 用bring, 表达动作还没有发生, 用forget to do sth“忘记去做某事”。故选C。
15.答案：C
解析：句意为:——汤姆,记得周五之前把这本书还回去。——记住了。Got it意为“记住了; 明白了”,符合语境,故选C项。
二、
16.答案：C
解析：根据she was not there及Wang Yong thought his mother可知,此处表示“他的妈妈”。故选C项。
17.答案：A
解析：wait意为“等待”; walk意为“走”; run意为“跑”; sleep意为“睡觉”。根据语境可以判断王勇等了20分钟。故选A项。
18.答案：D
解析：根据he knocked on the door和no one answered the door可知他敲了门,但没人开门,故说明他没有钥匙。故选D项。
19.答案：B
解析：second意为“秒”; minute意为“分钟”; day意为“天”; week意为“周”。由Wang Yong thought his mother was in the toilet 可知此处表示几分钟后,故选B项。
20.答案：C
解析：由上文中的no one answered the door可知此处应选C项。
21.答案：A
解析：friendly意为“友好的”; ugly意为“丑陋的”; serious意为“严肃的”:low意为“低的”。由invite Wang Yong to stay in their house可知邻层是“友好的”,故选A项。
22.答案：B
解析：sadly意为“难过地”; happily意为“开心地”; badly意为“糟糕地”; quickly意为“快地”。结合语境,故选B项。
23.答案：D
解析：touch意为“触碰”; admire意为“欣赏”; treat意为“对待”; thank意为“感谢”。此处表示王勇在离别之际表达谢意。故选D项。
24.答案：A
解析：由had a headache可知此处表示去看医生,故选A项。
25.答案：C
解析：fight意为“打架”; know意为“知道”; help意为“帮助”:leave意为“离开”。根据语境可知此处表示相互帮助。故选C项。细节理解题。
三、
A
26.答案：C
解析：细节理解题。根据“Nicky can make simple dishes.”可知,尼基可以做简单的饭菜。故选C项。
27.答案：B
解析：细节理解题。根据文中四款机器人玩具对应的儿童的年龄可知本题应选B项。
28.答案：D
解析：细节理解题。根据表格中对机器人玩具迈克尔的介绍可知D项正确。故选D项。
29.答案：A
解析：细节理解题。根据It is the smallest robot in our store可知,苏珊比其他三个机器人玩具更小。故选A项。
30.答案：D
解析：细节理解题。根据文中四款机器人玩具的价格可知,萨拉可以用380美元买奶牛和苏珊这两款玩具。故选D项。
B
31.答案：B
解析：细节理解题。由第二段第三句可知这名男子不喜欢西班牙的食物,故选B项。
32.答案：A
解析：词义猜测题。由第三段的said no和画线词后两句可知男子不想去希腊,故推测他对于去希腊的建议是感到“沮丧的”,故选A项。
33.答案：C
解析：细节理解题。由第三段最后一句“His neighbor went there and her hotel was only half-built.”可知此处应选C项。
34.答案：D
解析：细节理解题。由第四段第一句“Jane found out that flying to Florida was not a good idea because the woman didn't like being on planes for a longtime.”可知简认为佛罗里达不是个好的选择,因为那名女子不喜欢长时间坐飞机,故选D项。
35.答案：A
解析：主旨大意题。由第一段第一句“Last week a woman and a man came into Jane's travel agency to book a trip for August.”可知应选A项。
C
36.答案：D
解析：细节理解题。由第二段第三句"Looking at a smartphone for a long time can cause eye strain(劳损), headaches and dry eyes."可知，屏幕的蓝光会导致眼部劳损、头疼和眼睛干涩。故选D。
37.答案：C
解析：细节理解题。由第四段第三、四句"Doctors say that the light from those electronics at night may make you excited before you go to bed. Then it's hard for you to get enough sleep."可知，睡前看电子产品太长时间会影响睡眠质量。故选C。
38.答案：D
解析：推理判断题。由最后一段中的"To keep healthy, doctors and researchers strongly advise that you shouldn't use screens for long hours."可知，医生和研究者建议人们不要长时间使用电子产品，而非禁止各个年龄层的人使用电子产品。故选D。
39.答案：A
解析：文章出处题。通读全文尤其是第一段"It might be fun to use your smartphone, but be careful. Too much screen time may be harmful to your health."可知，本文主要介绍了长时间使用电子产品会对健康造成的损害。因此，本文有可能摘自一本科普杂志。故选A。
40.答案：B
解析：主旨大意题。通读全文尤其是第一段第二句"Too much screen time may be harmful to your health."可知，本文主要介绍了长时间看手机屏幕对人体健康造成的危害。故选B。
D
41.答案：C
解析：细节理解题。由第二段第二句I would have an English test可知答案，故选C。
42.答案：B
解析：词义猜测题。句意为：我按了邻居的门铃，又敲了门，但都没有人回答，故选B。
43.答案：D
解析：细节理解题。由第四段第五句 the firemen came and put out the fire quickly,故选D。
44.答案：A
解析：细节理解题。由第四段的第二句 my neighbor sleeping in his bedroom,第五段第二句the firemen came and put out the fire quickly,第二段第一句Last Sunday evening...及第五段最后一句they were happy,可知答案，故选A。
45.答案：C
解析：主旨大意题。文章讲述的是我发现了邻居家发生了火灾后打了火警电话并将邻居叫醒，救了他的故事，故选C。
四、
46.答案：Yes, it is.    
解析：根据Second Life is an online 3-dimensional, digital world可知第二人生是一个在线三维数字世界, 故填Yes, it is.
47.答案：A music festival.    
解析：根据Earlier this year, BBC Radio held music festivals and played an interview from inside the game.描述, 可知今年初BBC广播公司举办音乐节,在游戏中进行了面试, 故填A music festival.
48.答案：He wanted “Duran Duran” to take part in / join in the Second Life./ He wanted to be/ become part of the Second Life.    
解析：根据. I wanted “Duran Duran” to be part of it.故填He wanted “Duran Duran” to take part in / join in the Second Life./ He wanted to be/ become part of the Second Life.
49.答案：They will appear online as 3-D persons with the audience.    
解析：根据Each band member has a 3-dimensional person and it is hoped they will do their first online concert soon 故填They will appear online as 3-D persons with the audience.
50.答案：The bright future and great influence of Second Life with new 3-D technologies.
解析：根据段意罗兹说“第二人生”等新技术在音乐产业的未来将变得越来越重要。加入“第二人生”的人数正在迅速增长。一些计算机专家说这可能是未来的下一件大事, 故填The bright future and great influence of Second Life with new 3-D technologies.
五、
51.答案：future
52.答案：advice
53. 答案：upset
54. 答案：education
55.答案：feet
六、
答案：56-60 C; E; D; A; B
七、
答案：Dear students,
It is my great honor to speak here. Today, I am going to talk about how to protect the Earth. The Earth is our beautiful home. There are forests and rivers, mountains and fields. There are many different plants and animals on Earth, too. The Earth provides us with air, water and food. Therefore, it is very important for us to protect the Earth and let me share some ways with you.
First, we can take part in Earth Hour and turn off the lights for one hour. Besides, we should stop throwing away rubbish everywhere. In addition, we can plant more trees to make the Earth a better place.
Let’s try our best to protect the Earth. I hope everyone can work together.
解析：[总体分析]
① 题材：本文是一篇材料作文；
② 时态：时态以“一般现在时”为主；
③ 提示：写作要点已给出, 考生应注意不要遗漏要点“地球的重要性、保护地球的措施、号召大家保护地球”, 可适当添加细节, 完善写作内容。
[写作步骤]
第一步, 直接表明文章大意。直接说明文章主题是“保护地球”, 借“说明地球的重要性”来引出“如何保护地球”的内容；
第二步, 阐述保护地球的具体措施。从“参加地球一小时活动、不随地扔垃圾等”措施来介绍保护地球的具体做法, 可适当添加相关措施的内容；
第三步, 书写结尾。表达“大家一起保护地球”的号召。
[亮点词汇]
① share sth. with sb. 与某人分享某物
② take part in 参与
③ turn off 关掉
④ stop doing sth. 停止做某事
⑤ throw away 扔掉
⑥ in addition 此外
⑦ provide sb. with sth. 给某人提供某物
[高分句型]
① There are many different plants and animals on Earth, too.（There be句型）
② Therefore, it is very important for us to protect the Earth and let me share some ways with you.（“it is+形容词+for sb.+to do sth.” 句型）
③ In addition, we can plant more trees to make the Earth a better place.（动词不定式作目的状语）
④ Let’s try our best to protect the Earth.（“try one’s best+to do sth.” 句型）