用“what, why, which, when, how"填空，完成下面的疑问句。（注意首字母要大写）
1. ____________ is Li Ming doing? He is reading a book.
2. ____________ did you go to Shanghai? By plane.
3. ____________ do you like winter? Because I can ski.
4. ____________ season do you like best? Fall.
5. ____________ did you come to Canada? At 7: 00.
