If you take my ________, you'll make a lot of money in the trade.
| A．command | B．principle | C．attitude | D．tip |
—He failed in the exam again.
—He __________his teacher’s advice.
| A．should not have followed | B．should not follow |
| C．mustn’t follow | D．should have followed |
When firstto the market, these products enjoy great success.
| A．introducing | B．introduced | C．introduce | D．being introduced |
It is uncertain ______ side effect the medicine will bring about, although about two thousand patients have taken it.
| A．what | B．that | C．how | D．whether |
The English in the future will be quite different from the English of today. It is possible that some English words may even ________ completely.
| A．die down | B．die out | C．die off | D．die of |
Rainforests __________ and burned at such a speed that they will disappear from the earth in the near future.
| A．cut | B．are cut | C．are being cut | D．had been cut |