These boxes ______ for keeping the food clean and cool.
I went to the Window of the World in Shenzhen. It’s ____ great ______to see a lot of beautiful views in one day.
There ______ great changes in our hometown in the past fifteen years.
It _______ seven years __________ Hong Kong returned to China.
------- _______ you _______ the book ______ to the library yet. ------ Yes. I have.
The old man was not ______ to climb up the hill.