important us to listen carefully in class!A. That’s; ofB. It’s; forC. This is; forD. It’

问题补充：

important us to listen carefully in class!

A. That’s; of

B. It’s; for

C. This is; for

D. It’s; of

答案：

A. That’s; of

(答案→)B. It’s; for

C. This is; for

D. It’s; of

解析：

试题分析:强调句式， It is adj for sb to do sth，做某事对某人来说怎么样。本句中it是形式主语，指代后面不定式内容做形式主语，this和that无此用法，结合语境可知选B。