Question

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

Answer 1

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 it

2.inventing 不对,应该是invented,因为其逻辑主语The telephone (电话） 是invent(发明）所表动作的承受着,表被动,完成要用过去分词作定语

= which was invented