30.动名词、不定式短语与从句作主语时的主谓一致

动名词、不定式短语与从句作主语时，谓语动词用单数。To learn a foreign language is not so difficult as you think．

学一门外语并不像你想象的那么难。

Smoking is bad for health．

吸烟有害健康。

That he has won the game is known to us all．

他赢了这场比赛是众所周知的事。

提示：

what引导的主语从句所指的具体内容是复数意义时，谓语动词一般用复数。请对比:

What he needs is practical help，not spiritual help．

他需要的是实际的帮助，而不是精神上的帮助。

What you need is a quiet，reasonably warm and well-lit room and a comfortable chair and a table or desk to work at．

你需要一个安静、暖和、光线充足的房间以及能够开展工作的舒适的桌椅。

What we need are proper assessment centres．

我们需要的是规范的评定中心。

Clearly what you need are at least two helpers．

显然，你至少需要两个帮手。