1 The set of stamps,once(printed),will be popular with stamp-collectors.
问题描述：
1 The set of stamps,once(printed),will be popular with stamp-collectors.
为什么用printed而不用to be printed?
2Years later,these islands united as one,(forming) a new nation.
为什么用forming而不用formed?
3When we make the most ofthe waste materials,a lot of money(is saved).
为什么用is saved,而不用 saved
4It matters little how a man dies,but(what)matters much is how he lives.
为什么用what而不用it?
答
(1)printed为过去分词,有被动的完成的含义；to be printed是不定式的被动语态形式具有将来的含义.在这个地方讲的是已经盖过邮戳的邮票强调的是已经完成了的动作所以用printed.(2)ing形式有主动的含义,而ed有被动的含...