【简答题】饭店营销组合策略是 , , , 四大策略的有机组合与搭配。
【判断题】数字频带信号的解调通常用正交调制。所谓正交调制是因为在解调中用到了cos和sin两个正交的载波。
【判断题】数字频带信号的解调通常用正交调制。所谓正交调制是因为在解调中用到了cos和sin两个正交的载波。
【单选题】GPS天线必须( )安装,使金属底座保持水平,可用垫片予以修正。
【单选题】心理学家做过实验,服务员与客人视线相互接触的时间通常占交往时间的( ) 。
【单选题】particle is moving along an arbitrary curved path. Which statement is correct?
A.
The tangential acceleration is not zero.
B.
The normal acceleration is not zero.
C.
Because the velocity only has the tangential component, the normal acceleration must be zero.
D.
If the particle moves with a constant speed, the magnitude of the total acceleration must be zero. [ ]
【单选题】Which one of the following statements is true about axion?
A.
It is known for sure to exist although not enough evidence is available.
B.
It is another possible constituent of dark matter.
C.
The search for hypothetical particle has failed so far.
D.
If successful, experiment will prove it to be the sole form. of dark matter.