在轧制钢板时需要动态地监测钢板厚度，其检测装置由放射源、探测_爱下问搜题

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问题选择题

在轧制钢板时需要动态地监测钢板厚度，其检测装置由放射源、探测器等构成，如图所示。该装置中探测器接收到的是

[ ]

A.X射线

B.α射线

C.β射线

D.γ射线

答案

答案：D

选择题

It was playing computer games that cost the boy plenty of time he ____ doing his lessons.

A．might have spent

B．ought to have spent

C．must have spent

D．could have spent

单项选择题

( )用来描述数据的流程。

A．数据字典

B．数据流图

C．程序流程图

D．甘特图