Researchers discovered that plants infected with a virus give off a gas that_______ disease resistance in neighboring plants．

A．contracts

B．activates

C．maintains

D．prescribe

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参考答案

B。研究人员发现受到病毒感染的植物会释放出一种气体，这种气体可以激活其邻生植捌的抗病性。
考查动词辨析。contract意为“感染”；activate意为“激活，使活动”；maintain意为“维持”prescribe意为“规定；开处方”。根据句意应选activates。

A．persuaded

B．prompted

C．imposed

D．enlightened

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2 He spoke so _______ that even his opponents were won over by his arguments．

A．bluntly

B．determinedly

C．emphatically

D．convincingly

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3 The Eskimo is perhaps one of the most trusting and considerate of allIndians but seems to be_______ the welfare of his animals．

A．critical about

B．indignant at

C．indifferent to

D．subject to

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