—What is the boy doing?
—It's not necessary for you to be ________ about others' business.
| A．connected | B．combined |
| C．contributed | D．concerned |
It is requested that the machine be operated according to the________．
| A．introductions | B．explanations |
| C．suggestions | D．instructions |
－Mary，could you please post the letter for me while you are out?
－________
| A．I'd rather you didn't. | B．It's OK with me. |
| C．What for? | D．By all means. |
Tom's first job was at a local restaurant in his early twenties，________he worked for seven years.
| A．where | B．when |
| C．which | D．that |
She felt ________ awkward because of her bad performance on the stage.
| A．extremely | B．actually |
| C．frequently | D．exactly |
More and more carbon dioxide is being released into the air，________the more severe global warming effects.
| A．contributed to | B．to contribute to |
| C．contributing to | D．to be contributed to |