航空法的渊源最主要的是（）。
A.多边国际公约
B.双边协定
C.国内法及法院判例
D.国际惯例
参考答案：A
— Don't forget to go to see Mum on her birthday.
— No, I ______. [ ]
A. don't
B. can't
C. haven't
D. won't
等距抽样
