【问】 There is not very much experimental data________ a decision between the two possibili-ties.

A. on which to base B. which is based C. to base on D. to be based

答案为A。但这与关系代词which引导定语从句的用法不符。

【答】 关系代词which(whom)除用于引导定语从句外，还可以用于引导动词不定式，即介词+which(whom)+不定式。此动词不定式结构一般充当名词的定语。例如：

1.Yet now he had no pretext on which to prelong his stay. (Cronin)

现在他没有借口来延长他的逗留时间。

2. We can't decide whom to invite.

我们不能决定邀请准。

上题的意思是：

据以在这两个可能性之间做出决择的实验数据还不很多。