---- May I smoke here?--- If you , choose a seat in the smoking section.
—Is there any vaccine(疫苗) against H1N1 flu that can be used on humans? —No, but scientists are working to develop ________ .
Betty, still ______ excited, took away the box ______ with birthday presents for her.
--- I think it necessary that he _____ to New York but to London. --- I agree, but the problem is _____ he has refused to.
you be interested, I’ll tell you the whole story.
--You look upset. Anything wrong? --I failed in the physics exam again _____all the efforts I made.