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搜题
【单选题】
Modern handheld digital tachometers operated by counting light pulses returned to the unit byA.
the tach generator
B.
either the coupling or shaft
C.
a small bulb attached to the shaft
D.
a piece of reflective tape
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举一反三
【单选题】—Zhang Hua used to like history, didn't he? —Yes. With the help of Mr.Huang, he is ________ in _______ history now. [ ]
A.
much interesting; learn
B.
much interested; learn
C.
more interesting; learning
D.
more interested; learning
【简答题】北斗3号导航卫星系统中的IGSO卫星的高度是 km。