单选题 The main problem of the round-the-clock working system lies in ______.

A、 the inconveniences brought about to the workers by the introduction of automation
B、 the disturbance of the daily cycle of workers who have to change shifts too frequently
C、 the fact that people working at night are often less effective
D、 the fact that it is difficult to find a number of good night workers

【正确答案】 B

【答案解析】在第二段第四行，作者用unfortunately引出机器化全天二十四小时运转主要弊端在于：工业化工人通常每周一轮班，使工人刚刚适应了一种轮班工作时间，又马上调换另一种。这样，他的大多数时间既没有非常有效的工作，也没有非常有效的休息，故正确答案为B项，它意为“由于过频地改变当班时间而给日常循环的工人带来的麻烦”。因此选B项。