放置轮挡时，轮挡和轮胎之间的距离为多少?

Some states in the United States _______ people to carry guns.

Carelessness made him fall in his job _______.

Sometimes it is very difficult to _______ some of the English words. Even the native speaker can not help.

Students with _______ problems may apply for student loans.

Both sugar and salt can ______in water.

I have not heard anything from him since his _______.

Without a proper education, people could _______ all kinds of crimes.

Several loudspeakers are _______ from the ceiling and we can hear the speaker very clearly.

This morning in the class, our teacher lost his _______ at last because he could not stand any more.

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