About of the workers in the factory were born in.A. three-fifths 1970sB. three- fifths t

问题补充：

About of the workers in the factory were born in.

A. three-fifths, 1970s

B. three- fifths, the 1970s

C. three- fifth, the 1970s

D. three- fifth, 1970

答案：

A. three-fifths, 1970s

B. three- fifths, the 1970s

C. three- fifth, the 1970s

D. three- fifth, 1970

解析：英语中一般用基数词表示分数的分子，用序数词表示分数的分母。当分子是一时，分数的分母用单数形式，在表示分数时，当分数的分子大于一时，分数的分母要用复数形式。句意：这个工厂的大约五分之三的工人出生在七十年代。结合语境可知下文特指某个年代，故需用定冠词，选项CD结构有误，故选B。