My name ____ Jack. Liu Ying and Sun Mei ____ my friends.A. is; are B. is; is C. are; is
My parents like the music ____ is quiet and gentle.
We often see Betty ____ the old man with his housework.
In our city, _____ middle school students want to work as a teacher in the future.
I found _____ necessary to save energy and protect the environment.
________ beautiful these postcards are! Where did you get them?