An increased concentration of carbon dioxide and certain other gases in the Earth’s atmosphere ______ global warming.
| A．contributing to | B．contribute to |
| C．contributes to | D．to contribute to |
Mr Green showed his students some photos ________ at World Expo 2010 Shanghai.
| A．taken | B．being taken | C．to be taken | D．having taken |
A group of children are looking into the box, ________ about what can be inside.
| A．worried | B．curious | C．careful | D．sorry |
I must be off now. My friends ________ outside.
| A．wait | B．have waited | C．were waiting | D．are waiting |
David is a great teammate. He knows well how to work with ________.
| A．both | B．other | C．others | D．another |
I was about to walk over to Tom’ s seat when he ________ and left.
| A．turned up | B．got up | C．kept up | D．came up |