These boxes ______ for keeping the food clean and cool.
A．use B．are used C．have used D．were using
My parents asked me ______ my sister with her schoolwork.
A．help B．to help C．helping D．helped
Sir, would you mind not _____ here, please?
A．to smoke B．smoke C．smoking D．smoked
Miss Green isn’t in the office. She_______ to the library.
A．went B．was C．has gone D．has been
I didn’t hear your call because I ______ to music at that time.
A．listen B．will listen C．am listening D．was listening
My parents often______ me some gifts on my birthday.
A．buy B．will buy C．buys D．has bought
