—Look! A book is on the floor. Whose is it?—It ______ be Rick’s. It has his name on it.

－Mom, I’m leaving. －It’s raining. You’d better ________ an umbrella with you. 

—How did he get my telephone number?—You ________ it . You told him last week．

I can play basketball，but my sister ________．

The post office is about 1 kilometer __________.