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(共26張PPT)
Unit 5
Revealing
nature
Using language
Past perfect
BY MICHELLE
① Look at the sentences from the reading passage and answer the questions.
1. In sentence (a), which action happened first, “suspected” or “evolved from a common ancestor”
2. In sentence (b), which action happened first, “refused to believe” or “evolved from lower forms of life”
3. What does the structure had done indicate
It indicates the action happened before a certain past action.
Now look for more sentences with the past perfect tense in the reading passage, and summarise its use in your own words.
1. It was a young man who had left medical school without completing his degree.
2. ... he had recently received a letter from his father predicting that he would be “a disgrace to yourself and all your family.
3. After Darwin had spent some time in South America, his room on the ship was crowed with samples of the plants and animals he had collected.
4. At that time, people believed that all species had appeared on Earth at the same time, and had not changed since.
5. It seemed their beaks had evolved according to what food was available on that particular island.
6. Over time, it had slowly evolved into many new species.
Grammar: Past Perfect Forms
The past perfect is formed using had + past participle. Questions are indicated by inverting the subject and had. Negatives are made with had not.
Statement: You had studied English before you moved to New York.
Question: Had you studied English before you moved to New York
Negative: You had not studied English before you moved to New York.
肯定句 主語＋had＋過去分詞＋其他
否定句 主語＋ had＋not＋過去分詞＋其他
一般疑問句 Had＋主語＋過去分詞＋其他？
特殊疑問句 特殊疑問詞＋had＋主語＋過去分詞＋其他？
Summary
Grammar: Past Perfect Uses
表示在過去某一時刻或某個動作之前已經發生或完成的動作或存在的狀態。這個過去的時刻常用by, before, until等引導的短語或時間狀語從句來表示，也可以通過一個表示過去的動作或上下文來表示。
By nine o'clock last night, we had finished most of the work.
She had learnt about 500 English words before she went to middle school.
Grammar: Past Perfect Uses
表示過去某一時間之前發生的動作或存在的狀態一直持續到那時，并可能繼續下去，常同由for或since引導的表示一段時間的短語或從句連用。
I had been at the bus stop for 30 minutes when a bus finally came.
She said she had made great progress since she came here.
Grammar: Past Perfect Uses
在含有定語從句的主從復合句中，如果主從復合句敘述的是過去的事，則先發生的動作常用過去完成時。
She returned the book that she had borrowed.
The twins, who had finished their homework, were allowed to play badminton on the playground.
Grammar: Past Perfect Uses
過去完成時常常用在賓語從句(或間接引語)中，這時從句謂語表示的動作發生在主句謂語表示的動作(過去時)之前。
I thought that I had seen him before.
I was sent to the village last month to see how the development plan had been carried out in the past two years.
Grammar: Past Perfect Uses
在含有時間、條件、原因、方式等狀語從句的復合句中，若主從句動作的發生有先后順序，動作在前的要用過去完成時，動作在后的要用一般過去時。
I had finished cooking dinner before you came back.
I found the lecture hard to follow because it had started when I arrived.
Grammar: Past Perfect Uses
want, hope, mean, plan, intend等動詞的過去完成時可以用來表示過去未曾實現的想法、希望、打算或意圖，意為“本來……”。
I had hoped to be back last night, but I didn't catch the train.
We had intended to come and see you.
Grammar: Past Perfect Uses
過去完成時常用于某些固定句型：
在“hardly...when/ no sooner...than/ scarcely...when”句型中， 主句用過去完成時，從句用一般過去時。
I had no sooner reached home than it began to rain. ＝No sooner had I reached home than it began to rain.
It was＋一段時間＋since從句(從句用過去完成時) 。
It was at least three months since I had left Beijing.
Grammar: Past Perfect Uses
過去完成時常用于某些固定句型：
It was the first/second/...time＋(that)從句 (從句用過去完成時)。
It was the first time that I had chatted online in English.
by the time＋表示過去的從句＋主句(過去完成時)。
By the time I got to the station, the train had already gone.
by the end of＋表示過去的時間＋句子(過去完成時)。
By the end of last term we had learned 10 units.
Grammar: Past Perfect Uses
過去完成時用于虛擬語氣中，在wish, as if/as though, if, if only, would rather sb. had done sth.結構或從句中，常用過去完成時來表示與過去事實相反的假設。
If he had caught the early bus this morning, he would not have been late for class.
I would rather she hadn't done that.
Grammar: Difference from the Simple Past Perfect
過去完成時在時間上強調“過去的過去”，
而一般過去時強調過去某一特定的時間。
They had arrived at the station by ten yesterday.
They arrived at the station at ten yesterday.
在沒有明確的表示過去的時間狀語作標志時，謂語動詞表示的動作發生的時間先后須依據上下文來判斷：先發生的用過去完成時，后發生的則用一般過去時。
She was very happy and her whole family were pleased with her, too. She had just won first prize in the composition competition.
② Complete the paragraphs with the information from the given sentences.
began
had led to
developed
chose to
had made
③ Complete the online encyclopaedia entry with the correct form of the words in the box.
arrived
had lived
eaten
had introduced
competed
declined
Compete decline eat
Live introduce arrive
④ Work in pairs. Act out a role-play using the information in Activity 3. One of you will play the keeper of Lonesome George, and the other will play the reporter asking about George. Use the past perfect tense where appropriate.
⑤ Listen to the podcast and choose the statements that are made.
Biodiversity
1 Biodiversity is important.
2 Bacteria are always harmful to humans.
3 Some species of bacteria are used in food production.
4 Many species of bacteria recycle dead organic matter.
5 Our immune systems are able to fight off all germs.
⑥ Listen again and complete the fact sheet.
made up of cells
bricks that are used to build houses
thirty trillion
thirty-nine trillion
help with digestion
break down
⑦ Complete the boxes with the expressions from the podcast.
Do you know about......
Have you heard of ......
By the way......
Actually......
In fact,......
Speaking of which,…
Checking background knowledge
Adding information
⑧ Read the passage and answer the questions.
What species are mentioned and what is special about them
What other unusual life forms do you know of
Two species are mentioned: the blue whale and the water bear.
The blue whale is the largest animal species on Earth, which can grow up to almost 30 metres in length and weigh over 130,000 kilos.
The water bear is probably the toughest species, which can survive temperatures from 150 C to a below freezing -272 C.
⑨ Complete the paragraphs with the correct form of the words and expressions in the box.
is home to
are native to
scientific
habitats
ecosystem
appearance
primitive
ancestor
⑩ Work in pairs. Look at the pictures of the species native to different regions of China. Talk about biodiversity in China using the words and expressions in this section. Do online research to find more information.
Review past perfect tense.
Do further research on biodiversity in China and share your ideas with your friends.
THANKS FOR WATCHING

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