John waited at the bus-stop for nearly half an hour the bus finally arrived .
| A．when | B．as | C．before | D．while |
______ he was absent, I was expected to take his place greatly surprised me, for I didn’t have much experience.
| A．If | B．If that | C．That if | D．That |
. You’d better start it right away ______ you forget it.
| A．in case of | B．unless | C．before | D．since |
. If it ______ for the fence, he ______ into the river.
A. were not; fallen B. had not been; could have fallen
C were not; could fall D. had not been; could fall
. I could have offered you some help last weekend, but I ______ with my work at that time.
| A．would be occupied | B．was occupying | C．had been occupied | D．was occupied |
______ choice you make matters little to the final result of the discussion.
| A．No matter what | B．Whichever | C．Whatever | D．No matter which |