--There is a bad smell here.
--Oh, dear! I ______ the gas.

A．[ A ] must forget turning off

B．[ B ] must forget to turn off

C．[ C ] must have forgotten turning off

D．[ D ] must have forgotten to turn off

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参考答案

本题考查情态动词表示推测。推测已经发生过的事情，用must have done。forget to do sth．表示忘记去做某事(事情没有做)；forget doing sth．表示忘记做过某事(事情已做)。第一句指出，“这里有一股难闻的气味”，由此推知，“我”一定是“忘了”关煤气了。

1 —_____ may I_____ the book?
— For three weeks.

A．[ A ] How often; borrow

B．[ B ] How often; keep

C．[ C ] How long; borrow

D．[ D ] How long; keep

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2 Good-bye, Mr.Smith. I'm very pleased______.

A．[ A ] to meet you

B．[ B ] to have met you

C．[ C ] meeting

D．[ D ] having met you

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3 If you want _______, you should speak slowly and clearly to the listeners.

A．[ A ] to be understood

B．[ B ] to understand it

C．[ C ] understanding

D．[ D ] to understood

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