House prices vary from place to place and are usually high ________ there are famous schools.
| A．when | B．since |
| C．where | D．whether |
When the old man _______ to walk back to his house, the sun ________ itself behind the mountain.
| A．started; had already hidden | B．had started; had already hidden |
| C．had started; was hiding | D．was starting; hid |
In 1960, this was the longest bridge that __________.
| A．was ever built | B．had ever built |
| C．has ever been built | D．had ever been built |
―Why? Where is the key to the sound lab?
―Dear me! You _______ it in the taxi！
| A．have never left | B．never left |
| C．haven’t left | D．didn’t leave |
―What were you doing when I called you yesterday afternoon?
―I ________ my homework and I was starting to take a bath.
| A．had just finished | B．was finished |
| C．have already finished | D．was going to finish |
―What’s the matter? You look worried and restless.
―Oh, nothing really serious. As a matter of fact, I ______ of my graduation thesis. I have to hand it in soon.
| A．am just thinking | B．just thought |
| C．have just thought | D．was just thinking |