what引导的名词性从句中从句谓语动词的单复数情况：
what后面“什么时候用单数,什么时候用复数”根据动词后面的名词的单复数来定.
2.what引导的名词性从句做主语时,主句谓语动词的单复数情况：
(1)What在从句中做主语,主句谓语由what从句谓语决定.
1) What he’d like most for a birthday present is a camera.
(2)what在从句中做宾语,主句谓语由主句表语/宾语决定what they want are XX,XX&XX.
2) What his father left him are a few English books.