阅读下面的短文.在标有序号的空白处填入一个适当的词.或填入括号中动词的适当形式. No one knows 1 how the earth began, as

阅读下面的短文，在标有序号的空白处填入一个适当的词，或填入括号中动词的适当形式。

No one knows 1 how the earth began, as it happened so long ago．However, according to a widely 2(accept)theory, the universe began with a “Big Bang”3 threw matter in all directions．4 several billion years afterwards, the earth was still just a cloud of dust．What it was to become was uncertain until between 4.5 and 3.8 billion years ago 5 the dust settled into a solid 6．The earth became 7 violent that it was not clear whether the shape would last or not．It exploded loudly with fire and rock．They were 8 time to produce carbon, nitrogen, water vapor and other gases, which were 9(make)the earth’s atmosphere．What is even more important is that as the earth cooled down, water began to appear on its 10．

试题答案

答案：

1．exactly　2．accepted　3．that/which　4．For　5．when　6．globe　7．so　8．in　9．to make　10．surface