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问题 单项选择题

法洛四联症右向左分流量的大小主要取决于

A．室间隔缺损的大小

B．肺动脉狭窄的程度

C．主动脉骑跨的程度

D．主动脉直径的大小

E．右心室肥厚的程度

答案

参考答案：B

选择题

How many ____________ do you have?[ ]

A. books

B. a book

C. the book
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单项选择题

Good pencil erasers are soft enough not ________paper but hard enough so that they crumble gradually when used.

A．by damaging

B．so that they damage

C．to damage

D．damaging
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