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【单选题】
石英晶体多谐振荡器其振荡频率与电路中的( )。A.
电阻有关系
B.
电容有关系
C.
电阻和电容无关
D.
电阻和电容 有关系
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【简答题】Radar is used to extend the ________ of man’s sense of observing his environment, especially the sense of vision. A) validity B) liability C) capability D) intensity
【单选题】____ radar is to airplanes and ships, ______ eyes are to human's body.
A.
Such...as
B.
Just...as
C.
Such as...so
D.
Just as... so
【单选题】In restricted visibility the speed of a vessel without operational radar may be ________ enable effective avoiding action to be taken on sighting another ship．
A.
too low to
B.
too high to
C.
too high for
D.
too low for
【单选题】The basic principle of radar is illustrated by what happens when one shouts in a e. The echoof the shouting 11 the walls helps a person determine the size of i cave. With radar, however , the waves ar...
A.
through
B.
for
C.
on
D.
against
【单选题】My radar is not working．I require shorebased radar assistance．Is shorebased radar assistance ________ ？
A.
used
B.
available
C.
in use
D.
can be used
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