第四部分:单项选择(共10小题,每题1分,共10分)______ for our teachers, we’d never have been able to enter this university.
Flight BA 123 to Vienna is now boarding at_______.
He didn’t seem to mind_____________ TV while he was trying to study
I don't skate now, but I___________ when I was a kid.
We liked the oil painting better____________ we looked at it.
If human beings had been a bit less greedy and cruel, more birds and animals _____dying out.