1-------What is behind that tree -------There mu

问题描述:

1-------What is behind that tree -------There mu
1-------What is behind that tree
-------There must be a dog (sitting) behind it .
2.The telephone (inventing) by Alexander Bell is useful for people.
问:为什么1句sit要用现在分词?为什么2句invent要用ing形式?

1.(sitting) behind it 是现在分词短语作后置定语的,我们知道,现在分词是表主动,进行的.可以改为:that/ which is sitting behind it2.inventing 不对,应该是invented,因为其逻辑主语The telephone (电话) 是invent...