Pollution is a serious problem. Scientists have _______ some good ways to save it.
It’s ____ to play on the road. You’d better play in a ____ place.
It ________ him half an hour to drive home every day .
The dish looks good, but when I eat it, it ________very terrible.
As students, we are supposed to spend more time _________ .
When __________ he supposed to arrive yesterday?