问题描述：
8.many cities inthe southern part of the united states have difficulty ______traffic flowing when
8.many cities inthe southern part of the united states have difficulty ______ traffic flowing when it snows.
A)kept
B)to keep
C)keeping
D)in being kept
8.many cities inthe southern part of the united states have difficulty ______ traffic flowing when it snows.
A)kept
B)to keep
C)keeping
D)in being kept
问题解答：
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