A-A+
People flow from the countryside into cities.
问题详情
People flow from the countryside into cities. This happens ______.
A. sometimes
B. all the time
C. frequently
D. now and then请帮忙给出正确答案和分析，谢谢！
参考答案
正确答案：B
答案：B文章第四段指出，There is a constant flow of people from the country into the cities，其中用了constant一词，意为“不断的，连续发生的”，因此 B．all the time是正确答案。
