The same gestures, signs and so on, in other words, body language, may express different ideas or meanings in different cultures, so don’t use them _______ you are definitely sure of what they mean so as to reduce misunderstanding ______ the smallest number.

1. A.
   until; with
2. B.
   unless; to
3. C.
   until; by
4. D.
   unless; by

The same gestures, signs and so on, in other words, body language, may express different ideas or meanings in different cultures, so don’t use them _______ you are definitely sure of what they mean so as to reduce misunderstanding ______ the smallest number.

　 A. until; with　 B. unless; to　 C. until; by　　 D. unless; by

 ________ the same thing will happens again, the school should take effective measures to increase the students' awareness of the harmfulness of smoking.

   A. Once              B. As long as            C. Not until               D. In case

 ________ the same thing will happens again, the school should take effective measures to increase the students' awareness of the harmfulness of smoking.

   A. Once              B. As long as            C. Not until               D. In case