scientists have done a lot of research on A (H1N1) flu, there are still

题型：同步题难度：来源：

         scientists have done a lot of research on A (H1N1) flu, there are still some cases for further study.    [     ]
A. As
B. One
C. If
D. Although

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举一反三

While I       _ a Zhengjian Evening Paper in  the sitting room, the doorbell rang.[     ]
A.was reading
B.read
C.is reading
D.had read

题型：专项题难度：| 查看答案

If  Betty has time, she______ climbing with her parents tomorrow.[     ]
A. goes to
B. will go
C. went to
D. doesn"t go

题型：同步题难度：| 查看答案

You will be late ________ you leave immediately. [ ]
A. unless
B. until
C. if
D. or

题型：专项题难度：| 查看答案

________ she is young, she knows quite a lot. [ ]
A. When
B. However
C. Although
D. Unless

题型：专项题难度：| 查看答案

—It’s 10 o’clock now. I must go.
—It’s raining outside. Don’t leave ________ it stops. [     ]
A. when
B. since
C. while
D. until

题型：专项题难度：| 查看答案