伪像在声像图中A.十分罕见 B.视探测深度而定 C.视操作水平

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问题单项选择题

伪像在声像图中

A.十分罕见

B.视探测深度而定

C.视操作水平而定

D.视设备好坏而定

E.十分常见，理论上讲几乎任何声像图上都存在一定的伪像

答案

参考答案：E

单项选择题

与食管癌发病因素有关的是（）

A.过热、过硬食物慢性刺激

B.食物被多种真菌污染

C.水及土壤中钼的含量低，硝酸盐含量高

D.口腔不洁或龋齿

E.以上都是

单项选择题

The millions of calculations involved, had they been done by hand, ______ all practical value by the time they were finished.

A. could lose

B. would have lost
C. might lose

D. ought to have lost