选择题:In the past 50 years, there _____ a great increase in the amount of research ___

题目内容:

In the past 50 years, there _____ a great increase in the amount of research _____ on the human brain.

A.was...did

B.has been...to be done

C.was...doing

D.has been...done

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答案解析:

Typical of the grassland dwellers of the continent( ),or pronghorn.

Typical of the grassland dwellers of the continent( ),or pronghorn.

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The security of a country is( )related to the safety of the rest world.

The security of a country is( )related to the safety of the rest world.

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原始社会的仰韶文化陶瓷可分为三个类型:( )、庙底沟类型和马家窑类型,他们分别代表了仰韶文化的早、中、晚三期。

原始社会的仰韶文化陶瓷可分为三个类型:( )、庙底沟类型和马家窑类型,他们分别代表了仰韶文化的早、中、晚三期。

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