---- It’s very important for everyone to exercise. do you exercise?
----Three or four times a week.
A . How long B. How far
C. How soon D. How often
---- Is that girl Susan?
---- It ______ be her. She left for Beijing yesterday.
A. needn'tB. can't
C. mustn'tD. couldn’t
----Shall we go to the amusement park this Sunday, mum?
---- Sure, ________ I am busy.
A. unlessB. if
C. butD. or
This is the third time the famous scientist __________ the United States.
A. has been toB. has been in
C. has come toD. has gone
----Philip has gone to New Zealand．
----Oh，can you tell me________?
A．when did he leave B．when he is leaving
C．when he leftD．when is he leaving
No one can achieve success __________ effort.
A. beyondB. with
C. withoutD. beside
