Operation rooms should be kept free ______ bacteria of any kind.
| A．with | B．for | C．from | D．to |
—Are you pleased with what he has done?
—Not a bit ．It couldn’t be ________．
| A．so bad | B．much better |
| C．any worse | D．best |
_____ scores of times , but he still couldn’t understand it ．
| A．Having explained | B．Having been explained |
| C．Though it was explained | D．It was explained |
We waited and waited．_________ we had been looking forward to ．
| A．Then came the hour | B．Then did the hour come |
| C．Then the hour came | D．The hour then came |
________ their son away to college, the old couple got more room in the house．
| A．As | B．For | C．Through | D．With |
Fish have eyes and ________appears to be a nose, and they can hear, too．
| A．that | B．which | C．it | D．what |