问题 单项选择题

10kV配电系统发生单相接地故障时,故障相电压指示与非故障相电压指示()。

A、都升高

B、都下降

C、都不变

D、故障相电压指示下降与非故障相电压指示升高

答案

参考答案:D

阅读理解

阅读理解

                                                    

    The zebra belongs to the horse family.One of nature's great mysteries is why the zebra has stripes.One

theory is that the stripes help the zebra cool down.On hot days the black stripes get a lot hotter than the

white area of the zebra and under the black stripes there are special layers of fat for protection.Hot air then rises off the black stripes,forcing colder air down around the white areas,cooling the zebra down.This,

however,is just a theory.The stripes can also confuse predators (食肉动物) when zebras stay with other

animals in great numbers.

     Zebras have excellent hearing and eyesight and can run at a speed of up to 35 miles per hour (56

kilometers per hour).They also have a powerful kick that can cause serious injury to a predator,like a

lion,or an African wild dog.Usually the lead male of the herd stays at the back of the group to defend

against predators if necessary,while the females and youngsters run from danger.

     Zebras are herbivores and feed mostly on grasses,although they also might eat the leaves and stems (茎) of bushes a bit.They eat grasses for many hours each day,using their strong teeth.Spending so much

time chewing wears the zebra's teeth down,so their teeth keep growing all their lives.As the dry season

arrives and the grasses die back,zebra herds travel to find more food and water holes for drinking.Most

zebras have no specific territories.They travel from place to place,never staying in one area very long.

1. What can be inferred from the first paragraph?

A. There are different opinions about why the zebra has stripes.

B. The black stripes help the zebra live through cold days.

C. The zebra can easily be attacked by predators.

D. The zebra always travels with other animals.

2. According to the passage,herbivores are________.

A. animals that have specific territories

B. animals that only eat plants

C. animals that kill and eat other animals

D. animals that live in groups

3. The zebra has strong teeth all their lives because their teeth________.

A. only chew soft grasses

B. are used all day

C. are always growing

D. are kept clean

4. Which of the following statements about zebras is TRUE?

A. They have poor eyesight and hearing.

B. Their stripes can confuse predators.

C. They can run 56 miles per hour.

D. They usually stay in one area all their lives.

5. Which of the following TV programs might the passage be adapted for?

A. Hobbies & Leisure    

B. Everyday Tips

C. Digital Stadium      

D. Discoveries

阅读理解

阅读理解

     A lot of people are their own enemies. They regard themselves as unlikely to succeed in college and

often feel that there have been no accomplishments (成就) in their lives. In my first year of college

especially, I saw people get themselves down too quickly. There were two students in my class who failed the first test and seemed to give up immediately. From that day on, they walked into the classroom carrying defeat on their shoulders the way other students carried textbooks under their arms. When they

disappeared for good(长久地), no one took much notice, for they had already disappeared in spirit after

that first test.

     I have really wanted to shake them by the shoulders and say: "You are not dead. Be proud and pleased that you have brought yourself here to college. Breathe. Hope. Act." Such people should not use

self-doubts as an excuse for not trying. They should pull themselves together and get to work. They should start taking notes in class and trying to learn. Above all, they should not give up without even trying.

1. The phrase "get themselves down" (Para. 1) probably means ______.

A. tell lies  

B. lose confidence    

C. avoid dangers    

D. waste time

2. When the two students dropped out (退学), no one took much notice because ______.

A. they had long lost heart in class performance

B. they were absent from class too often

C. they didn't get on well with other students

D. they were so much cut off from the rest of the class

3. According to the passage, the two students failed in their study because of their ______.

A. shyness    

B. proudness    

C. self-doubt    

D. laziness

4. The author thinks that the two students should ______.

A. give up their college education        

B. learn from other students

C. feel happy because they are in college      

D. try hard before giving up