They kept trying _____ they must have known it was hopeless.
| A．if | B．because | C．when | D．where |
Don’t treat the vase as if it _______ made of steel.
| A．is | B．was | C．were | D．had been |
Although we met with some difficulties in building the railway, we were still _____ about finishing it before the deadline.
| A．consistent | B．enthusiastic | C．responsible | D．optimistic |
There are some health problems that, when _____ in time, can become bigger ones later on.
| A．not treated | B．not being treated | C．not to be treated | D．not having been treated |
Hardly ________________ she heard the strange scream coming from behind a tree.
| A．had she walked out of the woods than |
| B．did she walk out of the woods when |
| C．had she walked out of the woods when |
| D．she had walked out of the woods when |
It is important to have your eyes examined regularly to check for any sign of eye disease that may not have any ________.
| A．symptom | B．shadow | C．treatment | D．convenience |