3. Scientist (感到不解) as to why the whale had swum to the shore.

2. What happened to the ship (仍然是个迹) .

根据括号内的汉语提示补全下面句子。

1. (令我不解的) was why he left the country without telling anyone.

[语境展不]阅读下面句子，并试着归纳puzzle的意思及用法。

1. My sister likes doing crossword puzzles.

2. Scientists have been trying to solve this puzzle for years.

3. The findings of the survey puzzle me — they’ re not at all what I could have expected.

4. Susan' s been puzzling about / over this strange letter for weeks.

[自我归纳]puzzle既可作名词,也可作动词。

★作名词时，意为:①谜，智力游戏(句1) ;②难题，谜般的事物(句2) 

★作动词时，意为 “”,常用于以下结构:puzzle sb.使某人困惑

(句3) ; puzzle about / over sth.苦苦思索，仔细琢磨(句4) 。

2. What is even more important is that as the earth cooled down,water began to appear on its surface?

(P26)

[分析]

① 本句是一个主从复合句。

② 主句是What is even more important is,that 引 导从句。

③ 主句中包含二个由what引导的主语从句，that从句中

包含一个由 引导的时间状语从句。

[句意]更为重要的是，地球冷却了下来，地球的表面就 开始出现了水。

[仿写]更为奇怪的是，我下公交车时，又看见了那位老 太太。

1. What it yas to become was uncertain until between 4. 5 and 3. 8 billion years ago when the dust settled into a solid globe. (P25)

[分析]

① 本句是一个主从复合句。

② 主句是 What it was to become was uncertain until between 4. 5 and 3. 8 billion years ago,when 引导 从句。

③ 主句中包含一个由what引导的主语从句，what在从句中作 。

[句意]随后它会变成什么没人能知道，直到38-45亿年 前，这团尘埃才慢慢地形成一个固体的球状物。

[仿写]杰克打算做什么我不知道，直到第二天早上，他 才告诉了我他的计划。

Task IV. Read the text and decide whether the following statements are True (T) or False (F) .

1. The earth was in the shape of a cloud of dust after the “Big Bang”.

2. Carbon dioxide,nitrogen,water vapour and other gases formed the earth' s atmosphere.

3. The harmful gases and acids came from the oceans.

4. Reptiles came into being before amphibians.

5. Mammals gave birth to young babies and produced milk for them.

6. Life on the earth has much to do with how people look after it.

Task III. Read the text and combine the two halves of the sentences.

1. Atoms                        A. provided oxygen for the oceans and seas.

2. The earth explosion               B. combined and formed stars.

3. The water on Mars                 C. stops the heat escaping from the earth.

4. The extremely small plants           D. could live on land and in the water.

5. Amphibians                      E. produced carbon dioxide,nitrogen,water vapour and other gases.

6. Reptiles                        F. suddenly disappeared and no one knows the reason.

7. Dinosaurs                        G. disappeared later.

8. Carbon dioxide                     H. mostly lay eggs to produce younger generations.

Task II. Read Paragraph 4 and complete the following chart showing the development of the living things on the earth.

1.2.3.4.5.

Task I. Read the text and fill in the blanks in the chart below. Try to understand how life began and developed on the earth.

1.2.3.4.5.6.