用括号中所给单词的适当形式填空。
The playground is always_____________ (cover) with the snow in winter.
These beautiful stamps are well worth __________ (collect).
We should keep the candle _________ (burn) for three minutes.
It can take __________ (thousand) of people to make a movie.
Sally prefers __________ (stay) at home to going out on Sundays.