50Hz交流电干扰
参考答案:
当排列通过高压输电线时,在地震记录上会出现50周交流电干扰,其特点是频率稳定,一般都在50±3Hz.
The young dancers looked so charming in their beautiful clothes that we took ____pictures of them.
A.many of
B.a large amount of
C.a plenty of
D.masses of
若,则k的值为( ).
A.1
B.1或-2
C.-1或2
D.-2
E.2