They kept trying _____ they must have known it was hopeless.
| A．if | B．because | C．when | D．where |
His shop was so well managed that he sold in just 5 months ________ his competitor sold in a year.
| A．how | B．what |
| C．whether | D．why |
China's reform and opening has been going on for ________ is like about 30 years now and it's really quite remarkable.
| A．that | B．which |
| C．what | D．it |
It is worth considering ________makes “I am a singer” so popular through China.
| A．what | B．why |
| C．how | D．that |
Life is like a tale. ________ matters is not how long it is, but how good it is.
| A．Which | B．That |
| C．What | D．Whose |
—Can you tell me if Tom has finished his homework?
—I've no idea. He ________ it this morning.
| A．has being doing | B．had done |
| C．is doing | D．was doing |