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【单选题】

What is omni-directional antenna?

A.
An antenna which is capable of line-of-sight communication with a satellite without requiring any pointing.
B.
Generally it is used on an Inmarsat-B MES.
C.
Generally it is used on an Inmarsat-F MES.
D.
This is a kind of directional antenna.
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参考解析:
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【单选题】原子吸收光谱仪中,产生共振发射线和共振吸收线的部件是

A.
光源和原子化器
B.
原子化器和光源
C.
光源和单色器
D.
原子化器和单色器

【单选题】以下痕迹中属于动态痕迹的是( )

A.
站立赤足迹
B.
打击工具痕迹
C.
擦划工具痕迹
D.
撬压工具痕迹