One of the firms I applied to has offered me a job but I _____ my options open until I hear from the others.
| A．have kept | B．will have kept |
| C．am keeping | D．keep |
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 |
I have been living in the United States for twenty years, but seldom __________ so lonely as now.
| A．have I felt | B．I had felt | C．I have felt | D．had I felt |