Question

________ does Lin Feng usually clean the floor of his own bed-room? Once a week.

1. A.
   When
2. B.
   What day
3. C.
   How long
4. D.
   How often

Answer 1

D
答案选“D”。英语中要表示“多久间隔”发生一动作的提问时常用How often结构，回答时常用： once a month，twice a day，every week，sometimes，always，never等时间状语。而 How long常用来就表示持续性时间状语提问的。意为“持续、延续多久”。
1)—How often does your mother come to see you?
你妈妈多久来看你一次？
—Often . /Sometimes . / Once a week .
经常/有时/每周一次。
2)—How often was he late for work last season?
上季度他迟到过吗？
—Never. 从来没有。
3)—How long have you been in the army? —Nearly ten years .
你在部队服役多久了？近十年了。