人为调节三相异步电动机转子转速的方法有三种,即改变转差率调速、改变磁极对数调速和改变

题型:单项选择题

问题:

人为调节三相异步电动机转子转速的方法有三种,即改变转差率调速、改变磁极对数调速和改变定子()调速。

A.电源相数

B.电源频率

C.电源品质

D.电源输送方式

考点:电工电工综合练习电工综合练习题库
题型:单项选择题

呋塞米()

A.可导致听力减退和暂时性耳聋

B.可引起女性面部多毛、男性 * * 女性化

C.可致血糖升高

D.可引起巨幼红细胞性贫血

E.可致颅内出血加重

题型:单项选择题

马克思科学地揭示了人类社会发展的客观规律,指出人类社会最终将发展到 [ ]

A、资本主义社会

B、社会主义社会

C、 * * 主义社会

D、大同社会

题型:单项选择题
电气化铁路的输电线常用图所示的方式悬挂在钢缆上.钢缆的A端固定在电杆上,B端连接在滑轮组上.滑轮组由a、b、c三个滑轮构成,配重P由多个混凝土圆盘悬挂在一起组成,配重的总重为G,若不计摩擦和滑轮的重量,则以下说法中正确的是(  )

A.a为动滑轮,B端钢缆受到滑轮组的拉力大小约为3G

B.a为动滑轮,B端钢缆受到滑轮组的拉力大小约为G

C.a、c为动滑轮,B端钢缆受到滑轮组的拉力大小约为3G

D.a、c为动滑轮,B端钢缆受到滑轮组的拉力大小约为G

题型:单项选择题

急性早幼粒细胞白血病起病初期常表现为弥散性血管内凝血。

题型:单项选择题

Some of the keys have a special use. There are referred to as command keys. The 3 most common are the Control or (66) , Alternate or (67) and the Shift keys though there can be more (the Windows key for example or the Command key). Each key on a standard keyboard has one or two characters. Press the key to get the lower character and hold Shift to get the upper. Disk Drives - All (68) need a drive to get information off - or (69) - and put information on the disk - or (70) . Each drive is designed for a specific type of disk whether it is a CD, DVD, hard disk or floppy. Often the term ’disk’and ’drive’are used to describe the same thing but it helps to understand that the disk is the storage device which contains computer files-or software - and the drive is the mechanism that runs the disk.

A.read

B.write

C.speak

D.tell

更多题库