The twins look exactly the same. ______ of them are in my class.
A．Each B．Both
C．Either D．None
— I don’t think students should use mobile phones at school.
—______. They really have a bad influence on our study.
A. I agree with you B. Not at all
C. No problem D. It’s my pleasure
Many scientists believe that robots ______ able to talk like humans in 50 years.
A．were B．are
C．will be D．have been
— Why does the earth look blue in space?
— Because most of the earth’s surface ______ by water.
A．covers B．is covered
C．cover D．are covered
Look! The model is walking to us. ______ nice dress!
A．What B．What a
C．How D．How a
— What were you doing ______ I knocked at the door?
— I was sleeping.
A．unless B．once
C．when D．while
