— I rang you up last night but nobody answered.— Oh I usually off my phone at about 9:0

问题补充：

— I rang you up last night, but nobody answered.

— Oh, I usually off my phone at about 9:00 p.m.

A. switched

B. have switched

C. switch

D. had switched

答案：

A. switched

B. have switched

(答案→)C. switch

D. had switched

解析：考查时态：句意：昨晚我打电话给你，但是没有人接电话。--哦，我通常下午九点关手机。因为是通常做…，用一般现在时，选C。