(2013·北京，21)Volunteering gives you a chance ________ lives, including your own.

A．change  B．changing  C．changed  D．to change

________ several times，but he still doesn't know how to do it correctly.

A．Although I've taught him

B．I've taught him

C．Having been taught

D．Having taught

Information technology is taught in most schools，________ we have entered the information era.

A．so  B．while

C．for  D．still

It's really very dangerous.One more step，________ the baby will fall into the well.

A．or  B．so  C．but  D．and

There is still much to discuss；________，we shall return to this topic at the next meeting.

A．yet  B．therefore

C．otherwise  D．however

Knowledge is the food of thought ________，as long as it is put in our brain，we will grow wiser.

A．but  B．when  C．then  D．and

The number of the employees has grown from 1,000 to 1,200.This means it has risen ________ 20 percent.

A．at  B．by  C．to  D．with

—What do you want to do ________ those old boxes?

—To put things in when I move to the new flat.

A．by  B．for  C．of  D．with

His best－known painting that is ________ all praise will be on show in the National Gallery early next month.

A．without  B．within  C．over  D．beyond

Wuhan and Chongqing are among the most important cities in China ________ their size and population.

A．in terms of  B．in case of

C．in view of  D．in favor of