【题目】It is of great importance _______ parents say and do in family life, which may have a life-long effect on their children.
A. what B. that
C. how D. why
在线课程【答案】A
【解析】
试题分析：A.什么；B. 引导词；C.表示方法和程度，怎么样；D.为什么；
It为形式主语，真正的主语为what引导的从句，what在从句中作say和do的宾语。