It is essential to have an alphabetical index with any numerical system. This involves more work in setting up the system and maintaining it（）.
A. signing
B. marking
C. layering
D. keeping it in good order
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Please submit your application before 2 o’clock（）.
A. hand in
B. hand down
C. hand off
D. hand out
Leave the next two lines （）for the tutor’s comments.
A. blank
B. to beto be blank
C. being blank
D. be blank
在掺黏土混凝土中对黏土的品质要求有；所掺用黏土其黏土粒含量不低于40%，塑性指数不小于17，含砂量( )，有机物含量小于3%。
A. 小于5%
B. 10%
C. 大于20%
D. 不低于40%
What a secretary should do after a conference （）.
A. do nothing but serve the boss well.
B. leave the minutes unprocessed
C. keep records of the business transacted
D. all of them
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