Bob called to tell his mother that he couldn’t enter the house, for he ________ his key at school.
In the middle of the night, there suddenly came a loud thunder, _____ the alarms of the cars parking below us.
. The government is cautious because they are afraid that a new policy on taxation would ______the political balance of the country.
The American Foundation for the Blind has been trying to figure out how to make public libraries __________to blind readers .
Since Shanghai won the right to host the World Expo, over half a million people have volunteered to ___________in all the Shanghai Expo projects .
If you don’t resist smoking heavily like that , you will have to suffer the _______sooner or later .