With the help of high technology, more and more new substances ______ in the past years.
| A．discovered | B．have discovered |
| C．had been discovered | D．have been discovered |
If the motorbike driver had slowed down when he turned, the accident could have been _____．
| A．avoided | B．prevented | C．escaped | D．annoyed |
Some farmers are no longer _____ with two harvests per year; they are now striving for three．
| A．associated | B．acquainted | C．satisfied | D．annoyed |
None of us expected Mr．Johnson to _____ at the party．We thought he was still abroad．
| A．turn in | B．turn on | C．turn up | D．turn over |
Be careful when you surf the Internet．If you download a virus into your computer ______, you will not open your files．
| A．on purpose | B．by accident | C．at random | D．on average |
The news that Shenzhou VII returned to the earth successfully _____ throughout the country．
| A．stretched | B．expanded | C．extended | D．spread |