E-mail, as well as telephones, ______ an important part in daily communication.
| A．is playing | B．have played | C．are playing | D．play |
To improve their oral English, everyone in the class is supposed to ______ actively in these discussions.
| A．participate | B．attend | C．enter | D．take |
Stronger and more lasting memories are likely to be formed ________a person is relaxed．
| A．where | B．unless | C．when | D．although |
Nearly four hundred supermarkets in Beijing are preparing to dim(使暗淡) their lights ________ the "Earth Hour 2010" on Saturday night．
| A．honor | B．honoring | C．to honor | D．having honored |
A salty diet may increase the risk of stomach cancer ________ 10 percent, South Korean researchers found in a study of more than 2 million people．
| A．at | B．to | C．by | D．for |
The first textbooks ______ for teaching English as a foreign language came out in the 16th century.
| A．to be written | B．written | C．being written | D．having written |