-- Excuse me, sir, smoking in the gas station.-- Oh, I'm really sorry.A. doesn't allow B. isn't allowed C. aren't allowed
---- Is that girl Susan? ---- It ______ be her. She left for Beijing yesterday.
----Shall we go to the amusement park this Sunday, mum? ---- Sure, ________ I am busy.
This is the third time the famous scientist __________ the United States.
----Philip has gone to New Zealand. ----Oh,can you tell me________?
No one can achieve success __________ effort.