— These days I can only sleep for four or five hours at night as I’m too busy with my research work..
— If you keep going on like that, you are sure to sooner or later.
A. get down
B. break down
C. calm down
D. put down
网友回答
A. get down
(答案→)B. break down
C. calm down
D. put down
解析：这是一组对话。上文，那些天，因为我忙于我的调查研究工作，每天晚上我只能睡四到五个小时。下文，如果你持续那样，我保证你迟早会垮掉。get down下来break down（健康、精神）垮下来calm down安静put down放下，根据题意，故选B。