1) in possession of：占有
e.g. He is in possession of this house.
in the possession of：被占有
e.g. The keys are in the possession of the door keeper.
2) in spirit：在内心，在精神上
e.g. In spirit, at least, these laws were very fair.
in spirits：情绪或心情(好、坏等)
e.g. He is in poor spirits because of his failing in the exam.
3) keep up：继续，保持
e.g. They entered into a correspondence which was kept up for almost ten years.
keep up with：与……齐步前进，跟上
e.g. With their help, he has kept up with the class.
4) look about：环视
e.g. He looked about him with great interest.
look about for：四处寻找
e.g. She was looking about for the key she had just lost.
5) look up：向上看
e.g. He looked up and nodded to me.
look up to：尊敬
e.g. It must be rewarding to be looked up to by so many people.
