题目内容
根据句意填上合适的介词
This wall is a defense ________ the sea．
根据句意填入适当的介词或副词
I recognized the man ________ whom Ishook hands at a party．
It was dark and there was nobody ________ whom she could turn for help．
He defended his comrades ________ harm．
He said that he killed the man ________ self defense．
