不定式的进行体和完成体是不能作定语的。语法书好像没有解释为什么不能。

我猜想，不定式、现在分词和过去分词作后置定语其实是定语从句的简略式，省略了关系代词和动词be。例如：

the meeting to be held = the meeting which is to be held.

the meeting being held = the meeting which is being held.

the meeting held yesterday = the meeting which was held yesterday.

英语中没有哪种定语从句省略which和be之后能够得到the meeting to be being held或者the meeting to have been held。也许这就是不定式的进行体和完成体不能做定语的原因。