A left－luggage office is a place where bags ________ be left for a short time，especially at a railway station.
| A．should | B．can | C．must | D．will |
Maybe you have been to many countries, but nowhere else __________ such a beautiful place.
| A．can you find | B．you could find |
| C．you can find | D．could you find |
I failed in the final examination last term and only then __________ the importance of study.
| A．I realized | B．I had realized |
| C．had I realized | D．did I realize |
Only when your identity has been checked __________.
| A．you are allowed in | B．you will be allowed in |
| C．will you allow in | D．will you be allowed in |
The old couple have been married for 40 years and never once __________ with each other.
| A．they had quarreled | B．they have quarreled |
| C．have they quarreled | D．had they quarreled |
Only after my friend came __________.
| A．did the computer repair | B．he repaired the computer |
| C．was the computer repaired | D．the computer was repaired |