有一读者问： 有这样一道题： 就划线部分提问：
(1)He came here an hour ago .
答案是：
(2)How long ago did he come here?
问答案正确吗？
答案是正确的。类似情况还有how soon, how often, how long等，例：
(3)How soon will you be back?
(4)How often do you play tennis?
(5)How long does it take to go there by bus?
