13．She was often heard ____.

　A．sing

　B．singing

　C．sung

　D．to sing

12．Everybody is busy ____ ready for Christmas and buy Chiristmas presents.

　A．get

　B．getting

　C．to get

　D．got

11．One day when Edison was five years old, his father saw him ____ on some eggs.

　A．siting

　B．sitted

　C．sitting

　D．sat

10．It's time for supper now. Let's ____ it.

　A．stop to have

　B．stop having

　C．to stop to have

　D．stopping to have

9．We kept ____ the ball to each other, and they began to get angry.

　A．to pass

　B．passing

　C．pass

　D．past

8．I saw him ____ basketball with Jack an hour ago.

　A．plays

　B．to play

　C．played

　D．play

7．She said that she felt someone ____ in the room.

　A．to smoke

　B．smokes

　C．smoked

　D．smoking

6．They stopped ____ ,but there was no more sound at all.

　A．to listen

　B．to hear

　C．listening

　D．to listen to

5．It's very nice ____ you to ____ me about it.

　A．for; tell

　B．of; say

　C．to; speak

　D．of; tell

4．The boy enjoys ____ the radio in the morning.

　A．listening

　B．listening to

　C．listen to

　D．to listen