第四部分：任务型阅读（共10小题；每小题1分，满分10分）
请认真阅读下列短文，并根据所读内容在文章后表格中的空格里填入一个最恰当的单词。
The year is 2094．It has been announced that a comet (彗星) is heading towards the Earth. Most of it will miss our planet, but two pieces will probably hit the southern half of the Earth．
On 17 July , a piece four kilometers wide enters the Earth’s atmosphere with a massive explosion ．
