名词性从句中选择从属连词,连接副词的区别

应该是名词性从句中连接代词,和连接副词的区别.从句中缺主语、宾语、表语等成分时考虑连接代词,从句为主谓宾完整时用连接副词...
____he said is true.
这个句子中有主语从句,且从句中缺主语,应填上连接代词what.
I want to know ______he told a lie to his teacher.
A、what B、that C、why D .who
这个句子中有宾语从句,从句______he told a lie to his teacher句意完整,只考虑填连接副词 故选C