arbon we produce和the carbon produced by car，为免重复，故使用that来替代the carbon，故为that of men，故答案为D．注意区分：It 特指，代指上文提到的同一个事物．That 特指，单数可数名词或者不可数名词，同类但不是同一个，one泛指，代指单数可数名词．

点评 本题考查指示代词的用法．学生应根据语境选用合适的指示代词．

Let us suppose it is now about A.D. 2060. Let's make believe it is about 47 years from now. Of course, things have changed and life is very different.

Voyages to the moon are being made every day. It is as easy to take a holiday on the moon today as it was for the people in 1960 to take a holiday in Europe. At a number of scenic spots on the moon, many hotels have been built. In order that everyone can enjoy the beautiful scenery on the moon, every