问题 选择题

以下行为与对应的原理解释不相关联或错误的是(  )

A.喷射CO2扑灭木材火灾--CO2不可、也不支持燃烧且隔绝空气

B.洒水扑灭火灾--降低可燃物的着火点

C.用隔离带扑灭森林火灾--使可燃物脱离燃烧环境

D.用黄沙扑灭酒精着火--使之与空气隔绝

答案

A、二氧化碳既不能燃烧也不能支持燃烧,且密度大于空气,这就可以使二氧化碳气体覆盖在燃烧物上方,隔绝燃烧物与空气的接触,隔绝氧气而熄灭.此项的行为与原理关联正确,不选;

B、向燃烧物洒水可以降低燃烧物温度,当温度低于着火点时,可燃物的燃烧就会熄灭,并非是降低可燃物的着火点.此项原理解释错误.故选;

C、撤离燃烧现场的可燃物也是常用的灭火办法之一,扑灭森林火灾时设置隔离带就是撤离可燃物而灭火.该项关联正确,不选;

D、黄沙覆盖在燃烧的酒精上,使酒精隔绝氧气而熄灭.故此选项解释正确,不选.

故选B

阅读理解

阅读理解。

     Some children are flying kites near the river. They are very high and Peter can see them in the classroom.

His mother's friend Mrs White comes to see his mother this morning and brings a kite to him. She gives it to

him after lunch. It looks like a bird. He wants to fly it but his mother doesn't let him do so.

     "It's time to go to school," says the woman,"or you will be late for class. You can play it after school."

The boy is sorry, but he says goodbye to Mrs White and goes to school. Now he's in the classroom but he's

looking out. He doesn't listen to Miss Black. She writes something on the blackboard and then turns to the

class.

     "Name nine things with milk in them, Peter," she says.

     The boy doesn't hear her and still sits there. A boy after him taps his back and he understands it. He stands

up and Miss Black asks him the question again. He thinks for some time and then says, "Yes, madam, tea,

coffee, cake and… er… six cows."

1. Where is Peter when some children are flying kites?

A. Near the river.

B. In the classroom.

C. At home.

D. At Mrs White's home.

2. Mrs White comes to see Peter's mother _________.

A. this morning

B. this evening

C. after lunch

D. this afternoon

3. Mother lets Peter fly the kite after school and _________.

A. tells him to go to school

B. tells him to do the homework

C. they begin to have lunch first

D. tells him to listen to the teacher

4. Peter looks out of the classroom, so _________.

A. he wants to go home

B. he can answer the question

C. he doesn't hear Miss Black

D. he can fly a kite

5. Peter only knows _________.

A. six cows

B. three things with milk in it

C. how to fly a kite

D. tea and coffee

填空题 案例分析题