用括号内所给单词的适当形式填空
1. It usually takes me half an hour __________(walk) to school.
2. The government should pay much attention to the __________(increase) population.
3. The grand piano takes up too much __________(room).
4. I think Beijing is one of the __________(beautiful) places in the wor
ld.
5. No one __________(know) when he will be back.
