Mr. Brown is 70 this year. Although he is very old, ____ he works very hard.
Suddenly, they heard ______ whisper from the bushes behind _______tree on the left.
—Do you like to sleep with the windows ________? —Yes, I’d like to feel the air and wind.
---Can we swim in the river? ---_______. It's dangerous to swim here.
There is a_______ tree in front of my classroom
The exchange_______ homes are in the UK. I want to take_______ to the Great Wall.