一台三相异步电动机,PN=7.5kW,额定电压UN=380V,nN=960r/min

题型:问答题

问题:

一台三相异步电动机,PN=7.5kW,额定电压UN=380V,nN=960r/min,定子Δ接法,频率为50Hz。额定负载运行时,定子铜耗为474W,,铁耗为231W,机械损耗45W,附加损耗37.5W,

计算其转子铜耗.

考点:电机装配工中级电机装配工(中级)
题型:问答题

从所给的四个选项中,选择最合适的一个填入问号处,使之呈现一定的规律性()

 

A.

B.

C.

D.

题型:问答题

In a US study, researchers measured (测量) the happiness of 4739 people over 20 years. The study found that a person’s happiness depends on the happiness of people he connects with. Surprisingly, it also found that happiness spreads not only between direct friends, but also among friends of your friends’ friends! And those good feelings seem to have the greatest influence among friends of the same sex (性别).

“People with more good friends are less likely to develop depression (情绪低落) and worry,” says Dr. Toupey Luft. “Though you can’t choose your family or workmates, you do have control over friendships.” With a little effort, you can add more positive (正面的,积极的) relationships to your social circle. Here’re the suggestions:

“Nobody is all positive or all negative,” says Luft. “But there are people you may feel more positive. Use that as your way to check people and keep records.” When spending time with others, pay attention to your feeling. Are you feeling tired and unhappy?To help you keep records, Luft suggests taking a moment when you get home to write down what your feeling is when around them.

While it’s great to gather with positive friends, it’s also good to stay with others in the same life situations. “But if you’re all just complaining (抱怨) and nothing is changing, it’s not healthy,” says Luft. Are your friends negative, or are you doing most of the complaining? Considering the answers to these questions can help you decide if you want to stand in front of them. Or you could let the relationship disappear slowly.

Sometimes your hobbies can lead to true friendships. Check out newspapers and websites to find a group or class for something you enjoy. These friends can always be there for you and can care each other through difficulties, illness and death.

Not into groups? Look for individual (个人的) communication instead. Luft says, “Set small goals, such as having coffee with one new person, and develop friendship according to a plan. If someone suggests going for lunch sometime, set a date.”

“If you’re feeling disappointed (失望) with a friend, try talking about what you both need,” says Luft. For example, tell her what you want during hard times in your lives. While your friend may need to be left alone, you may want caring phone calls. With some friends you laugh and have fun together at the movies—and that can be enough. With others, you pay attention to your deep connection.

小题1:What does your happiness depend on, according to the passage?

A.How people you connect with feel.

B.How many friends you have.

C.What situation you are in now.

D.What kind of friends you have.小题2:What does the first suggestion want us to do?

A.To measure our happiness.

B.To check people around.

C.To join a group for hobbies.

D.To leave negative friends.小题3:Which of the following is true?

A.We often have many friends during good times but few during hard times.

B.It’s necessary to complain about something but not right to do so for long.

C.Joining a group can bring better friendship than making individual friends.

D.All the suggestions tell us to add positive relationship to our social circle.小题4:The underlined sentence in the last paragraph means that ______.

A.when your friend is sad, you should call her up

B.when your friend leaves you, you need comfort

C.friends’ needs may be quite different sometimes

D.people may behave differently during hard times

题型:问答题

聚焦式滤线栅的使用,以下不会产生切割效应的是

A.中心线倾斜方向与铅条方向平行

B.中心线倾斜方向与铅条方向垂直

C.X线管与胶片的距离超过栅焦距2倍以上

D.中心射线左右偏离栅中心距离超过允许范围

E.将聚焦式滤线栅反置使用

题型:问答题

患者常某,呃逆一周余,症见呃声低长无力,气不得续,泛吐清水,脘腹不舒,喜温喜按,面色淡白,手足不温,纳呆便溏,舌质淡,脉细弱。

治疗首选()。

A.理中汤

B.丁香散

C.橘皮干姜汤

D.补中益气汤

E.肾气丸

题型:问答题

空气能热水器是通过吸收空气中的热量来制造热水的“热量搬运”装置.其工作原理是:空气能热水器在工作时,吸收空气中的能量Q,消耗的电能为W,通过热交换使水吸收的热量为Q,即Q=Q+W,所以它的热效率(

Q
W 
的值)可以达到300%~500%.已知某型号空气能热水器的热效率为400%,电功率为1400W,当用此热水器将100kg的水从15℃加热到55℃时[水的比热容为4.2×103J/(kg.℃),干木柴的热值为1.2×107J/kg].求:

(1)水吸收的热量;

(2)水吸收的热量相当于完全燃烧多少千克的干木柴所释放的热量;

(3)空气能热水器完成上述加热过程所用的时间.

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