We must keep our room clean , for dirt and disease go , you know .
Because paper is very expensive, we must ____ it with other things.
The parents have the ____ to teach their children to follow all school rules.
We're going to be meeting there on a regular ____.
The elephant and the monkey went to the river, but the water was ____ and the monkey was afraid.
______ regular exercise is very important,it's never a good idea to exercise tooclose to bedtime.(2011 .天津)