Tom, clean up the broken glass _________ someone walks on it.
The man and the horse _____ fell into the river were drowned.
----- Mr. Chen is a teacher and works very hard. -----_______ his wife.
____ he has been chosen to work as a teacher in the mountain village ____ him feel very proud.
The question is very important. It really needs _______.
Follow the directions on the bottle carefully when _______.