问题补充：
79. There are only five minutes left before the train leaves. You should run .
A. fast as possible as you can
B. as quickly as you can
C. as fast as possible
D. possible as fast as you can
答案：
A. fast as possible as you can
B. as quickly as you can
(答案→)C. as fast as possible
D. possible as fast as you can
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