1．They were in time to produce carbon dioxide, nitrogen，water vapour and other gases, which were to make the earth's atmosphere. (P25)

　　它们最终产生了二氧化碳、氮气、水蒸气和其他气体，从而形成了地球的大气层。

　　★in time及时；终于；总有一天

　　写出下列句中in time的含义

　　①Andy knew he could not reach the house in time.及时

　　②You'll succeed in time because you are always working hard.总有一天

　　③Working hard made him successful in time.终于

　　in no time　　 立刻；马上

　　at no time 决不(放在句首时，句子用部分倒装)

　　at a time 每次；一次

　　at one time 曾经；一度

　　at the same time 同时

　　from time to time 有时；偶尔

　　④At_one_time I grew crazy about skating. However, I fell onto the ground from_time_to_time,_but I knew that I would at_no_time be skilled if I lack of practice.

　　曾经我对滑冰十分痴迷。然而我却有时摔在冰面上，但是我知道如果缺乏训练我绝对不会熟练。

　　2．What many scientists believe is that the continued presence of water allowed the earth to dissolve harmful gases and acids into the oceans and seas. (P26)

　　很多科学家相信，由于地球上长期有水存在，使地球得以把有害气体和酸性物质溶解在海洋里。

　　★harmful adj.有害的

　　(1)be harmful to ...　　　 对......有害

　　(2)harm n. & vt. 伤害；损害

　　do harm to sb.＝ do sb. harm 伤害某人；对人有害

　　There is no harm in doing sth. 做某事没有坏处

　　(3)harmless adj. 无害的；无辜的

　　①It is harmful to your eyes to read books in the bus.

　　在公共汽车上看书对你的眼睛有害。

②Playing computer games will not only do great harm (harm) to your physical health, but it