题干
-How do you come here? You look tired(累的). -________.
A：On bike
B：By bike
C：By a car
D：By a train
答案(点此获取答案解析）
B
-How do you come here? You look tired(累的). -________.
A：On bike
B：By bike
C：By a car
D：By a train
满足：存在正整数
，对于任意正整数
都有
成立，则称数列
，
