【问】 在分裂句(强调句)中可以使用关系代词that或who (whom，whose).能否使用which呢?

【答】 CGEL(P.1387)的说法是：“Although whose is allowed in cleft sentences...whom andwhich are only marginally possible...”(“尽管whose可用于分裂句……但是whom和which只是勉强可用。”)因此，我们在CGEL中没有查到which用于强调句的实例。但是，在其他著作中，尤其是在科技英语著作中有时还是能读到这类句子：

1. It was a key which I found in his pocket.

我在他的衣袋里找到的是一把钥匙。

2. It is heat which makes matter expand and melt.

正是热使物质膨胀和熔化。

3. It is the release of nuclear energy within the Sun which enables it to send out so muchenergy to the Earth.

正是太阳内部释放出来的核能使太阳能够对地球发射出如此多的能量。

4. ...it is the theatrc at Oxford and not at Cambridge which is on the verge of extinction

…(NCE 4，L.13)

……是牛津的讲坛而不是剑桥的讲坛正频于消亡……

当which之前有介词时，实际上不能用于分裂句：

It was the dog to which I gave the water. (CGEL)

上面的句子只能看作是含有定语从句的句子。