问题 单项选择题

支架和拱架应预留施工拱度,在确定施工拱度值时,应考虑支架受力产生的弹性和非弹性变形,支架基础的沉陷和结构物本身受力后各种变形。其中还应考虑()汽车荷载(不计冲击力)引起的梁或拱圈的弹性挠度。

A.1/5

B.1/4

C.1/3

D.1/2

答案

参考答案:D

单项选择题 A1/A2型题
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 zebra

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