问题 多项选择题

有关模板、拱架和支架的拆卸的质量控制要点有()。

A.不承重的侧模板,应在混凝土强度能保证混凝土表面及棱角不致损坏的情况下方可拆除,一般在混凝土抗压强度达到2.5MPa时方可拆除侧模

B.一般跨径不超过4m的梁和板应达到混凝土设计强度等级的50%;跨径超过4m的梁、板应达到混凝土设计强度等级的75%时,方可拆除

C.抽拔芯模的时间,以混凝土抗压强度达到0.4MPa~0.8MPa为宜

D.石块或混凝土预制块拱桥,须待砂浆强度达到图样要求时才能卸架;如图样无规定,一般须达到砂浆设计强度等级的75%

E.跨径小于10m的拱桥,在拱上建筑完成后卸架;中等跨径的实腹式拱,在护拱完成后卸架;中等跨径的空腹式拱,在拱上建筑立墙完成后卸架。裸拱卸架需事先进行验算

答案

参考答案:A, B, C, E

阅读理解

阅读理解。

     Years ago, many zoos kept all kinds of animals in small cages. Small cages made it easy for people to

see the animals, but a small cage is not a good place for an animal to live in.

      Today zoos keep animals in different kinds of cages.The cages are very big and open. They usually

have plants and little lake. The cages look like the animals' habits.

     Zoos help to protect all kinds of animals. They protect animals in the zoo and they protect animals

in the wild. How do they do this? Zoos teach people how animals live in the wild. Zoos want people to

help protect the animals' wild habitats.

     Many plants and animals are going extinct (灭绝). Mammoths, which related with the Asian elephants,

are now extinct. There are no mammoths in the world today. Scientists say that seventy-four different

kinds of living things go extinct every day!

      Zoos are working together to stop animals from going extinct.

1. Zoos kept animals in small cages so that people can _____. [ ]

A. protect them

B. see them better

C. feed them

D. save them

2. Today, zoos keep animals _____.[ ]

A. in bigger cages

B. in the wild

C. in smaller cages

D. in the field

3. To protect animals, zoos _____.[ ]

A. are trying to keep all kinds of animals

B. are trying to free the animals

C. teach people more about animals

D. want people to feed the animals

4. A mammoth is a kind of _____ that has gone extinct. [ ]

A. plant

B. bird

C. animal

D. tree

5. An animal or a plant that is going extinct _____. [ ]

A. no longer exists (存在) in the world

B. comes into this world soon

C. becomes very dangerous

D. has fewer and fewer living members

单项选择题