5.做定语：

不定式做定语与先行词有动宾、主谓和解释先行词内容等关系。在时态上常是将来意义，现在分词做定语是现在时或进行时态意义;过去分词做定语则是完成时态意义。此外，不定式做定语时只能后置，不可前置，而单个分词做定语可前置，分词短语做定语则须后置。动名词做定语，须前置，且要重读，它表明先行词的用途。而分词做定语表明先行词的性质、特征和状态。

a swimming boy=a boy who is swimming

a swimming pool=a pool for swimming

the boiling water=the water that is boiling

drinking water=water for drinking

Today I have a letter to write.

Please find a man to help us.

It is a good chance to practise your spoken English.

I like reading books written by Lu Xun.

The woman standing over there is our English teacher.

The house to be built (=which will be built/which is to be built) next year will be our new library.

The house being built (=which is being built) now will be our new library.

The house built (=which was built) last year is our new library now.