Our teacher looked here and there on our playground ______ looking for something.
| A．even though | B．even if | C．as if | D．only if |
I met the teacher in the street yesterday ____ taught me English three years ago.
| A．which | B．when | C．where | D．who |
It will be quite a long time _____ she is back again, so don't be too cross with her.
| A．that | B．since | C．before | D．until |
I often go to the English corner to have a free talk with my classmates ____ I am busy.
| A．except that | B．except for | C．except when | D．except |
In order to continue to learn by ourselves when we have left school, we must ________ learn how to study in the school now.
| A．in all | B．after all | C．above all | D．at all |
Unless they are programmed by humans, computers are nothing more than big pieces of metal. But once _____ what to do, they show extraordinary power in carrying it out.
| A．taught | B．teaches | C．teaching | D．to teach |