单选题：The idea has been widely accepted ______ Beijing Opera shoul..

Make full use of your time________you can achieve what you desire.[ ]A．soB．orC．butD．and

_____ you call me to say you' re not coming, I'll see you at the theatre.[ ]A.ThoughB.Whether C.UntilD.Unless

The girl had hardly rung the bell ___ the door was opened suddenly, and out rushed her friend. [ ]A. before B. when C. untilD. since

We must take measures to stop various kinds of pollution ______ the environment gets worse. [ ]A. unlessB. untilC. beforeD. when

— Can you tell me how to learn English well? — Do more speaking, I think, ______ you will not be good at spoken English. [ ]A. then B. andC. or D. until