Whether they would support us was a problem. 他们是否会支持我们还是一个问题。

　　It was a problem whether they would support us. 他们是否会支持我们还是一个问题。

　　It remains to be seen whether it will do us harm or good. 它对我们是利是害，还得看看再说。

　(3)对关系代词型what引导的主语从句，通常直接将主语从句放在句首。如：

What we need is money. 我们需要的是钱。

What I want to know is this. 我想知道的就是这一点。

有时也可将助用形式主语。如：

　　It is clear enough what he meant. 他是什么意思很清楚。

(4)如果句子是疑问句，则必须用带形式主语it的结构：

　　Is it true that he is the girl's father? 他是那女孩的父亲，是真的吗?

　　How is it that you are late again? 你怎么又迟到了?

三、连词that的省略问题

引导主语从句的连词that 有时可省，有时不能省，其原则是：若that引导的主语从句直接位于句首，则that不能省略;若that引导的主语从句位于句末，而在句首使用了形式主语it，则that可以省略：

　　That you didn't go to the talk was a pity. 很遗憾你没去听报告。(that不可省)

　　It was a pity (that) you didn't go to the talk. 很遗憾你没去听报告。(that可省)

1.(2014上海期末)______ golf was first played in Scotland in the 15th century is generally agreed.

A. Whether B.Why C. That D. What

解析：根据句意"普遍认为高尔夫球最初是于15世纪在苏格兰进行比赛的。"本题考查主语从句，主语从句中不缺少任何成分，再根据句意可知答案。

答案：C。

2. (2014全国大纲)Exactly______ the potato was introduced into Europe is uncertain, but it was probably around 1565.

A. whether B.why C. when D. how

解析：根据句意"土豆被引进到欧洲的确切时间不能确定，但很可能在1565年左右"此处为主语从句的引导词，从around 1565判断，这里指时间。

答案：C。

3.(2014天津)I think_____ impresses me about his painting is the colors he uses.

A. what B. that C. which D. who

解析：根据句意"我认为他的画像使我印象深刻的是他对色彩的使用。"在主语从句中，所缺的词作主语且表示"物"，没有选择范围，所以用what引导。

答案：A。

4.(2014北京)Some people believe ______has happened before or is happening now will repeat itself in the future.