173.The most important thing about cotton in history is ____ part that it played in ____ Industrial Revolution.

A.不填；不填

B.the;不填

C.the;the

D.a;the

174.It is really ____ useful dictionary,_____ dictionary every one of us needs.

A.an;a

B.a;the

C.the;a

D.a;a

173.答案是C，

考查冠词的用法，第一空特指cotton发挥的作用，是特指；第二空中工业革命为专有名词，加固定冠词。

174.答案是D，

考查冠词的用法，第一空泛指；第二空同位语，补充说明。