Many teens don’t get enough sleep because they have too much homework to do which them u

问题补充：

Many teens don’t get enough sleep because they have too much homework to do, which them up at night．

A. makes

B. breaks

C. turns

D. keeps

答案：

A. makes

B. breaks

C. turns

D. keeps

解析：考查动词辨析：A. makes制作B. breaks打破C. turns转D. keeps保持，keep up是词组“维持，不低落”这里是“不能睡觉”，句意：很多年轻人没有足够的睡眠，因为作业太多，这使他们晚上不能睡觉。选D。