We must ______ the importance of using a foreign language as a tool．

[　　]

A．know　　　B．see　　　C．realize　　　D．recognize

The flood has caused ________ to the crops in the area.

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There are various ________ of birds in the world, but many have become extinct.

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The ________ of the school is quiet for the students are having a day off.

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He speaks English very fluently. He is ________ to have lived in America for some years.

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He has ________ a bad habit of biting his nail when he is thinking.

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The project got ________ after some days' delay.

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Choose the word or expression which is closest in meaning to the underlined part （选择与划线部分意义最相近的词语）：

The wine was knocked down to Mr Johnson for $30.

　　　[　　]

A. destroyed

B. stricken

C. sold at a low price

D. reduced

Choose the word or expression which is closest in meaning to the underlined part（选择与划线部分意义最相近的词语）：

People in far northern countries sometimes form small houses out of blocks of ice.

[　　]

A. take shape　　　B. appear

C. make　　　　　　D. develop

Choose the word or expression which is closest in meaning to the underlined part （选择与划线部分意义最相近的词语）：

We asked them to come to our party, but they declined.

[　　]

A. decreased　　　B. moved from bad to worse

C. refused　　　　D. agreed