what与that引导名词性从句时有何区别

what与that引导名词性从句时有何区别　　
 　　
what与that引导名词性从句时有何区别? 请看题：　　
—I think __________ he needs is more practice. 　　
—Yes. __________ he needs more practice is clear. 　　http://yingyu.chazidian.com
A. what, What                   B. that, That                  C. what, That                   D. that, What　　
此题应选 C。其余三项均可能被误选。what 和 that 都可以引导名词性从句，但有区别。如：　　
1. what 引导名词从句时，它在从句中要充当句子成分(主语、宾语等)，而 that 引导名词从句时，它在从句中不能充当句子成分。　　
2. what 引导名词从句时，它有词义(表示：什么；所……的[东西])；而 that 引导名词从句时，它没有词义。　　
请做以下试题，注意区别 what 和 that。如：　　
1. ________ you said is different from the thing ________he told us. 　　
A. What, what                        B. That, that　　
C. What, that                          D. That, what　　
2. —I think ________ he said is true.(http://yingyu.chazidian.com) 　　
—But don’t forget the fact ________he is a cheat. 　　
A. what, what                        B. that, that　　
C. what, that                          D. that, what　　
3. ________ surprised us most is ________he spoke English so well. 　　
A. What, what                         B. That, that　　
C. What, that                           D. That, what　　
答案：1. C     2. C     3. C