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问题 单项选择题

冠心病的确定诊断标准为

A．动脉粥样硬化性斑块形成

B．动脉内膜增厚、毛糙

C．心肌间质纤维增生

D．冠状动脉管腔内径狭窄≥50%

E．以上都不是

答案

参考答案：D

选择题

促成20世纪科学技术飞跃发展的理论基础是  [ ]

A、量子论和相对论

B、细胞学说和进化论

C、电流的磁效应和电磁感应现象的发现

D、元素周期律的发现
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选择题

When asked to explain _____ he did to make his students so fascinated with his lessons, the teacher paused and thought deeply.

A．what was it that

B．that what it was

C．what it was that

D．what was it
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