题目内容

一般把频率在()范围的声波叫做超声波。

A. 2KHz到20MHz
B. 3KHz到20MHz
C. 2KHz到25MHz

查看答案
更多问题

电动机转速提不起来的原因是重绕时()。

A. 进入杂物
B. 未烘干
C. 匝数过多
D. 匝数过少

电机、设备以及电缆等应尽可能不受灰尘、有害气体和()的损害

标准电压-48V的电信设备,其受电端子电压变动范围为()。

MV ATLANTIC 0200UTC POSN 33.55N 127.22E COURSE 088 DEGS SPEED 12.5 KTS SAILOR FELL FROM MAST SERIOULY WOUNDED AT HEAD. This cable says that().

A. the wounded had nothing wrong with his head
B. the injury was not serous
C. the injury happened at the mast head
D. a sailor injured at his head

答案查题题库