—Do you know when your friend ___? --I’m not sure. I will tell you when he _____?
There are many tall buildings on ____ sides of the street.
There are about 50____in our school.
–What did your mother say ? -- She asked _____.
Do you like Wang Fei_____ is very popular with most people.
–I’m sorry I really can’t work it out. —Try again, Liu Fang. It’s only ____ difficult for you. You can make it.