在单相异步电动机中获得圆形旋转磁场的条件是()。A、电机具有在空间位置上的相差90°

题型:单项选择题

问题:

在单相异步电动机中获得圆形旋转磁场的条件是()。

A、电机具有在空间位置上的相差90°电角度的两相绕组

B、两相绕组中通入相位差为90°的电流

C、两相绕组所产生的磁势幅值相等

D、两相绕组所加的电压相等

E、两绕组电流来自同一电源

考点:维修电工考试维修电工综合练习维修电工综合练习题库
题型:单项选择题

患者女性,20岁。被汽车撞伤,腹部持续性剧烈疼痛,伴口渴、头晕,不能行走。站立时,头晕加剧,并有心悸、气短,被急送医院。

提示:患者受伤后,无呕血及血便,无明显呼吸困难,未排尿,查体:神志清,面色苍白,体温36.5℃,脉搏115次/分,血压90/70mmHg。气管居中,左季肋部皮肤有肿胀。心肺无异常。腹式呼吸减弱,全腹压痛阳性,轻度肌紧张及反跳痛,移动性浊音阳性,腹部听诊肠鸣音减弱。血常规:WBC9.8×109/L,Hb105g/L。紧急的处理应是()

A.可适当饮水缓解口渴症状

B.输血

C.肌注度冷丁或吗啡

D.协助医师进行必要的化验检查

E.绝对卧床休息

F.立即建立静脉通道

G.监测生命体征

H.迅速了解受伤原因、部位及伤后症状表现

题型:单项选择题

阅读理解。

回答问题, 阅读下面短文,根据第1-3小题的具体要求,简要回答问题。

     Height is just one of the thousands of features your genes (基因) decide. In fact, because you have two

parents, your genes provide you a height that usually lands somewhere between the height of each parent. If

both your parents are tall, then most probably you will be tall, too, but if you have questions about how tall

you're going to be, ask your doctor if he or she can help you find it out.

     But genes don't decide everything. For example, eating an unhealthy diet can keep you from growing to

your full potential (潜力). Getting plenty of sleep and enough exercise will help you grow to the expected

height.

     No doubt (怀疑) you're wondering how fast you should grow. It depends. There's no perfect or right

answer. In general, kids grow about 2 inches (6 centimeters) a year between age 3 and the time when they

start puberty (when your body starts changing and becoming more grown up).

     Your doctor will know how your growth has been going over the years. Two centimeters here and 2

inches there are not nearly as important as the height you're at now, how you've been growing up to this point,

and what other changes your body may be going through.

     Don't be scared if you seem to have grown a lot in a very short time. Everyone has a growth spurt (高峰)

during puberty. The age for starting puberty is about 10 for girls and about 11 for boys. But it can be earlier

or later -between 7 and 13 for girls and 9 and 15 for boys.

     You'll usually begin to notice that you're growing faster about a year or so after your body starts to show

the first changes of puberty.

1. What is the Chinese for the word"puberty"?

_____________________________________________________________

2. Whom will you turn to if you want to know how fast and how tall you should grow?

(回答词数不超过1个)

______________________________________________________________

3. What's the main idea of the passage? (回答词数不超过8个)

______________________________________________________________

题型:单项选择题

由于石化能源存在污染及蕴藏量减少的问题,新能源一直被视为重要替代品,其中核能更是各国开发的____________。但日本核事故却引起大家对核能安全的______________,各国政府无不希望在短期内找出更安全、经济的新能源,以减少对石油长期的依赖。 依次填入划横线部分最恰当的一项是:

A.热点疑虑 

B.要点警觉 

C.重点忧虑 

D.基点警惕 

题型:单项选择题

最常伴发急性左心功能衰竭的疾病是().

A.肺梗死

B.室间隔缺损

C.肺动脉瓣狭窄

D.急进性高血压

E.主动脉窦瘤破裂人右心室

题型:单项选择题

主变压器启动风冷保护是该保护是根据负荷来启动风冷的保护,当达到定值时延时()秒启动主变风冷装置。

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