--- I called you last night but nobody answered. --- Oh I usuallyoff my cell phone by 8:

问题补充：

--- I called you last night, but nobody answered.

--- Oh, I usuallyoff my cell phone by 8:00 pm.

A. switched

B. have switched

C. switch

D. had switched

答案：

A. switched

B. have switched

(答案→)C. switch

D. had switched

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