what引导宾语从句时在从句中作主语、宾语或表语，表示“所„„的„„”例如：表示“……的东西或事情”，相当于“the thing that...; all that...; everything that....”
1、They’ve done what they can to help her. 他们已经做了他们能做到一切去帮助了。
2. 表示“……的时间”,相当于the time that：
After what seemed like hours he came out with a bitter smile.
似乎过了几个小时他才苦笑着出来。
The young girl was too frightened to speak, standing there for what seemed like hours.
小女孩吓得不敢说话，在那儿站了似乎几个小时。
3. 表示“„„的人”，相当于the person that„。
如： He is not what he was a few years ago. 他不是几年前的他了。
4. 表示“„„的地方”，相当于the place that„。
如： This is what they call Salt Lake City. 这就是他们称作盐湖城的地方。
In 1492, Columbus reached what is now called America. 1492年哥伦布到达了现在所称的美洲大陆。
5. 表示“„„的数目”，相当于the amount/number that„。
如： Our income is now double what it was ten years ago.
我们现在的收入是十年前的两倍。
The number of the students in our school has reached as many as 20,000, ten times what it was before liberation.
现在我校学生多达2万人，是解放前的十倍。
扩展资料：
写宾语从句注意事项：
A、宾语从句必须用陈述语序。但也有部分口语提问以疑问代词作主语。
False: He is wondering when can he finish this difficult job.
Right: He is wondering when he can finish this difficult job.
B、有时候可以用it作形式宾语，而把真正的宾语从句放在后面。
Bad: I thought that he could finish this job in just two hours impossible.
Good: I thought it impossible that he could finish this job in just two hours.
Bad: He left whether we should continue this project to my judgment.
Good: He left it to my judgment whether we should continue this project.
C、带有宾语从句的复合句的否定形式一般是否定主句。
Bad: I think he doesn’t like the English teacher.
Good: I don’t think he likes the English teacher.
D、主句 一般过去时态，从句也要用过去时态；具体细节请看第一部分。
False: He wanted to know why he is crying in the corner.
Right: He wanted to know why he was crying in the corner.
I make a list of what my kids will need for the coming season. (what作need的宾语）
I just wonder what makes him so excited. (what作主语）
May I ask what your plans are.(what作表语）
I want to know what color you like best. (what作定语，修饰color)本回答被网友采纳
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I want to know what book you like to read.
I want to know whick book you like to read best of the three.
在上面这两句话种，可以很清楚的看到what ＆which的区别
what 没有范围
which 是在有范围之内的一种选择