疑问词

疑问词 when, where, who, what, how

1.He bought three books yesterday
    Who bought three books yesterday
    What did he buy yesterday
    When did he buy three books

how long, how far, how often, why

1. They have been in China for three years
    How long have they been in China?
2. It is about 4 kilometers from Beijing to Xi'an
    How far is it from Beijing to xi'an?
3. They come to visit me once a week
    How often do they come to visit me?
4. She came late, because she missed the bus.
    Why did she come late?