英语选择性必修 第二册Unit 5 A delicate world评课ppt课件

这是一份英语选择性必修 第二册Unit 5 A delicate world评课ppt课件，共41页。PPT课件主要包含了Grammar， 1960s，吸收摄入，溶解的营养物质，依靠依赖，提供能量，以为食 ，捕食掠夺，Questions，Answers等内容，欢迎下载使用。
Vcabulary building
Listening & speaking
a. N visitr wuld think it surprising that the island is a UNESCO Wrld Heritage Site.b. N visitr wuld think that the island being a UNESCO Wrld Heritage Site is surprising.
Grammar: It as an empty bject
Lk at the sentences and answer the questins.
c. Experts felt it necessary t cme up with a plan t remve all the rabbits frm the island.d. Experts felt t cme up with a plan t remve all the rabbits frm the island was necessary.
1. What des “it” refer t in sentences (a) and (c)?
Lk at the sentences and answer the questins. Sentences (a) and (c) are frm the reading passage.
“It” in sentence (a) refers t “the island is a UNESCO Wrld Heritage Site”.
“It” in sentence (c) refers t “t cme up with a plan t remve all the rabbits frm the island”.
2. What is the difference between the sentences in each grup?
When the bject f a sentence is a that-clause (b) r an infinitive (d), we smetimes use “it” as an empty bject and put the real bject later t keep balance. Fr example, sentence (a) uses “it” as the empty bject f
“think”, referring t the real bject: “the island is a UNESCO Wrld Heritage Site”. Sentence (b) uses that-clause as the bject f “think”.
Wrk in pairs: Nw lk fr mre sentences with this structure in the reading passage, and summarise its use in yur wn wrds.
it 作为形式宾语的两种基本用法：
当动词不定式，动名词和从句在某个句中作宾语时，为了保持句子的结构平衡，常用it作形式宾语，而将真正的宾语放到句子后部去。
1） He fund it nt easy t learn a freign language well. 他发现学好一门外语是不容易的。2）I think it necessary that we have the meeting. 我认为我们开这个会是有必要的。
it 作为形式宾语的几种特殊情况：
1） 动词 + it + that 从句，常见于 take, have, put 等动词之后。 例：I take it that he will finish the task by himself. 我认为他能自己完成这项任务。
2） 动词 + it + when / if 从句，常见于appreciate, enjy, like, prefer 等动词之后。 例: We really appreciate it if yu culd d us a favur. 如果您能帮助我们，我们会很感激。
3） 动词 + it + 介词短语 + that 从句，常见于 we it t sb, take it fr granted 等结构中。 例：We we it t yu that we are still alive. 多亏有你，我们现在才仍然活着。
4） 动词 + it + 过去分词 +从句。 例：He made it knwn t everyne that he was right. 他让每个人都明白他是对的。
5） 动词 + 介词 + it + that 从句，常见于 lk t, depend n, insist n, stick t, answer fr 等结构中。 例：She insisted n it that she was inncent. 她坚持说自己是无辜的。
Rewrite the underlined parts using it as an empty bject.
The red-eared slider, a species f freshwater turtle, is native t the Suthern United States and Nrthern Mexic. Due t its cute appearance, many peple think keeping this turtle as a pet is a gd idea. Recent years have seen mre and mre pet sliders escaping r being released frm hmes, and sme wners believe t release them int the wild is n big issue.
These days, peple have fund t release these turtles int the wild is a threat t ther species. Experts cnsider wners keeping their pets in an enclsed area imprtant, and anyne unable t keep their pets shuld take them t an apprpriate animal shelter.
many peple think keeping this turtle as a pet is a gd idea
many peple think it a gd idea t keep this turtle as a pet
believe t release them int the wild is n big issue
believe it n big issue t release them int the wild
peple have fund t release these turtles int the wild is a threat t ther species
peple have fund it a threat t ther species t release these turtles int the wild
Experts cnsider wners keeping their pets in an enclsed area imprtant
Experts cnsider it imprtant fr wners t keep their pets in an enclsed area
Lk at the pictures f the Saihanba Natinal Frest Park and describe its changes using it as an empty bject where apprpriate.
present day
breakthrugh impssible likely unrealistic ...
grwinvestigateplant treestransfrm...
I think it a breakthrugh t transfrm a desert int a frest ...
Yu may refer t the wrds and expressins in the table fr help.
Nw wrk in pairs. Describe hw a place yu knw has changed using it as an empty bject where apprpriate.
1. absrb __________________ 2. disslved nutrients __________________3. rely n __________________4. prvide energy __________________
Vcabulary building: Ecsystems
Pay attentin t the wrds and expressins in bld.
5. feed n ____________________6. prey n ____________________7. break dwn ____________________ 8. release ____________________
Lk at the diagram and answer the questins.
1.What des the diagram shw?
The diagram shws a fd chain – the cnnectin between the living things.
2. What are the relatinships between the living things?
The living things are clsely cnnected with each ther by the fd they eat. Secndary cnsumers prey n primary cnsumers, primary cnsumers feed n prducers, and prducers
2. What are the relatinship between the living things?
absrb light frm the sun, and water and disslved nutrients frm the sil, which are prvided by decmpsers.
Cmplete the passage with the crrect frm f the wrds and expressins.
In a wdland ecsystem, trees and ther plants are prducers. They water, and take in nutrients frm the sil and energy frm the sun. Insects are an example f a primary cnsumer. They the prducers t prvide fd fr them, and are by secndary cnsumers: small mammals and birds. They the primary cnsumers. Wrms, fungi
and bacteria are decmpsers. They animal waste and the remains f living things. The chemicals these decmpsers fertilise the sil and give the plants the nutrients they need t grw.
Listening & speaking
Listening & speaking: Befre listening
• One f the ldest species in the ecsystem, the hney bee has been in existence fr millins f years.• A hney bee can fly as fast as 24 kilmetres per hur and its wings can beat 200 times per secnd.• In just ne jurney t cllect pllen and nectar, ne single hney bee can pllinate as many as 50 t 100 flwers.
Backgrund infrmatin
Listening & speaking: While-listening
Listen t the cnversatin and chse the true statements.
1. Bees are very imprtant t ur fd supply because they prvide hney.2. The bee ppulatin is declining.3. Withut bees, humans wuld die ut.4. All human crps depend n bees fr pllinatin.
5. If bees became extinct, ther insects culd pllinate enugh crps.6. Humans are respnsible fr the decline in the bee ppulatin.
A cmbinatin f things damages bee habitats, mainly ________________________________.
Listen again and cmplete the flw chart.
The bee ppulatin is ______________________. Accrding t statistics, bee numbers in the US _______________________in just ne year.
pesticides and climate changes
declining very quickly
have fallen by 17%
Withut bees, crps wuld ___________________. _____________ wuld nt be able t cmpensate fr the lss f bees, because __________________ _______________________ f the species f crps.
Animals that live n the crps _______________
be unable t reprduce
Other insects
bees are respnsible
wuld die ut
fr pllinating abut 70%
Listening & speaking: Summary
Yu must be kidding! • Are yu sure abut ... ? I dn’t believe it! • Check it ut fr yurself ... It’s a fact! • Accrding t statistics ... Dn’t frget that …
Cmplete the bxes with the expressins frm the cnversatin.
• Yu must be kidding! • I dn’t believe it! • Are yu sure abut ... ?
• It’s a fact!• Dn’t frget that…• Check it ut fr yurself... • Accrding t statistics...
Listening & speaking: Pair wrk
Wrk in pairs. Talk abut what wuld happen t the ecsystem if anther species died ut. Use the wrds and expressins in this sectin.