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【简答题】

对于漫反射式光电开关,粗糙表面反射回的光线强度必将 (填写大于、小于、等于)光滑表面反射回的光线强度。

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举一反三

【单选题】In the wake of 11 September, Visionics, a leading manufacturer, issued a fact sheet explaining how its technology could enhance airport security. They called it "protecting civilization from the faces...

A.
any way, the face-recognition technology is good enough to frighten the terrorists
B.
the industry will have to recognize the real situation and work hard to improve the technology
C.
all the claims are premature
D.
we must not expect too much

【单选题】光电开关的检测距离为( )。

A.
几毫米到几十毫米
B.
几厘米到几十厘米
C.
几米到几十米
D.
几千米到几十千米