https://online2.tingclass.net/lesson/shi0529/0008/8532/p123.mp3
https://image.tingclass.net/statics/js/2012
In a bad traffic jam, cars can be backed up for miles.
在嚴重交通堵塞時,車龍可能長達幾英里。
back up 有支持和援助的意思(看下例),用做被動語態(tài)時,back up也有堵塞的意思。
I always back you up.
我總是會支持你的。
The traffic is backed up.
交通堵塞。