they have been struggling against the snowstorm for ten hours.A. Up to nowB. By the time

问题补充：

, they have been struggling against the snowstorm for ten hours.

A. Up to now

B. By the time

C. From then on

D. In the future

答案：

(答案→)A. Up to now

B. By the time

C. From then on

D. In the future

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