When traveling alone in the mountains, you ’d better take a _______ with you in case you get lost.

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

The college students in China are _______ from smoking on campus because this will do them no good.

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

Whenmakingmoderncameras,peoplebeganto_______plasticsformetal.