15,6,17,9,20,7中，从左边数起，第4个数是(    )；从右边数起，9排在第(    )个。把这些数从小到大的顺序排一排。

(    )<(    )<(    )<(    )< (    )< (   )

I thought we'd be late for the concert, _____ we ended up getting there ahead of time. [ ]

A. but

B. or

C. so

D. for