Ⅰ.用所给词的适当形式填空
1．People have long ________(puzzle) over how the Egyptians moved such huge rocks.(2015·四川，阅读E)
2．As an old teacher he ________ (witness) the great changes that have taken place in the school in the past thirty years.
3．There is no ________ (possible) that he’ll fall in love with Kate.
4．Now it ________ (occur) to him that his farm had much potential and that the death of the cow
