The earth is a special planet in the solar system. The explosion of the earth produced carbon, nitrogen, vapor and other gases, 【小题1】 (make) the earth’s atmosphere. What is even more important is _【小题2】 as the earth cooled, water which is fundamental to the 【小题3】 （develop） of life appeared and stayed on the surface. The continued presence of water allowed the earth to dissolve 【小题4】 (harm) gases into the oceans and this produced a chain reaction which made it possible for life to develop.
Many millions of years later, the _【小题5】 （arrive） of small plants encouraged the development of early shellfish 【小题6】 all sorts of fish. Then, with the first green plants appearing on land, land animals appeared and dinosaurs developed and existed on the earth for millions of years. Then Dinosaurs’ sudden disappearance made the rise of mammals possible on the earth. They were different from all life forms 【小题7】 ever existed in the past because they produced young from within their bodies. Finally, some small clever animals with hands and legs 【小题8】 (appear) and spread all over the earth. Thus they, in their turn, have bee 【小题9】 most important animals. However, they are putting too much carbon dioxide into the atmosphere. So for millions of years to e, 【小题10】 life will continue on the earth will depend on whether the present problem can be solved.making
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(答案→)making
解析：
【小题1】making 本句中的现在分词making在句中做结果状语，表示意料之中的结果，地球的爆炸产生了多种气体，这些气体形成了地球的大气层。
【小题2】 that 本句是一个表语从句，that引导起这个表语从句，在句中不充当任何成分，只起引导和连接作用。
【小题3】 development 横线前面有the表示这里应该使用名词development的形式，指人类生命的发展。
【小题4】harmful 后面有名词gases说明这里应该使用形容词harmful对名词进行修饰限制。
【小题5】arrival 前面有定冠词the后面有介词of说明横线要填写的是名词arrival。
【小题6】 and 小型植物的出现导致了贝类动物和各种鱼类的发展。这两个短语是并列关系，故使用and连接。
【小题7】that 本句是一个定语从句，that指代前面的先行词life forms在句中做主语。
【小题8】 appeared 本空的动词appeared是一个谓语动词与后面的spread是并列结构，都使用过去时。
【小题9】the 后面有最高级most的形式，故使用the。
【小题10】whether 本句是一个主语从句。地球上的生命是否能继续取决于现在的问题是否能够被解决。