‘动名词作主语时谓语动词用单数形式’和这类似的语法有哪些,有关语法越多越好

不定式短语、动词的-ing形式和名词性从句作主语,谓语动词用单数形式.
Doing experiments is a good way to find out answers to questions.做实验是找到问题答案的好方法.
To learn foreign languages is not so difficult as you think.学一门外语并不像你想象的那么难.
That I shall work with you is a great pleasure.我能和你在一起工作是极大的快乐.
但要注意：
what引导的主语从句,谓语动词通常用单数,但所指的具体内容是复数意义时,谓语动词可用复数形式.
What we want is more time.我们需要的是更多的时间.
What they need in that area are doctors and nurses.他们那个地区需要的是医务工作者.
What she left him are some old photos.她给他留下的是一些旧照片.

主语从句，非谓语动词

不定式做主语，也是用单数