问题
选择题
20．We met _____ and have become good friends since then.
A．by mistake
B．by accident
C．by ourselves
D．by the way
答案
答案：B
考查短语辨析。by mistake 由于疏忽所犯得的错误，by accident 偶然的，by ourselves 靠我们自己，by the way 顺便说，句意：我们偶然遇见了从那时起我们成了好朋友。所以选B。