John _______ to be a polite man. But in fact he is veryrude.

When making modern cameras , people began to_______ plastics for metal.

Some lazy men would rather _______ than work.

Professor Smith is also the _______ of the international program office. If you have any problem when you study here,you may go to him for help.

Free medical service is _______ to nearly all the college students in China.

This river is so big that it is impossible to build a _______under it without modern technology.

Carelessness made him fall in his job _______.

In the United States, the foreign policy is decided by the ________ government, not by each state.

It is not ---_______ for me to return all the books to the library now because I still need some of them for my research.

Both sugar and salt can ______in water.