问题 填空题

仔细观察化学实验现象,常常会有意想不到的发现.某同学用一干冷的小烧杯罩在甲烷燃烧的火焰上方,杯壁上出现水珠,一会儿火焰逐渐微弱,移开烧杯后火焰又恢复正常.他想了想,于是又用一氧化碳做了相同的实验,也观察到了同样的火焰变化现象.你认为火焰变微弱的原因是:______;他用一氧化碳做相同实验的目的是______.(其他合理均给分)

答案

因为甲烷燃烧生成二氧化碳和水,烧杯内氧气浓度降低,同时生成的二氧化碳也不支持燃烧,导致了火焰变微弱.用一氧化碳代替甲烷重做实验出现相同的现象,说明火焰变化不是水造成的.

故填:烧杯内O2浓度降低或热的CO2聚集在烧杯中;为了排除水蒸气对实验的干扰或进行对比实验.

选择题
阅读理解

When Pat Jones finished college, she decided to travel around the world and see as many foreign places as she could while she was young. Pat wanted to visit Latin America first, so she got a job as an English teacher in a school in Bolivia. Pat spoke a little Spanish, so she was able to communicate with her students even when they didn’t know much English.

Once, A sentence she had read somewhere struck her mind: if you dream in a foreign language, you have really mastered it. Pat repeated this sentence to her students and hoped that some day she would dream in Spanish and they would dream in English.

One day, one of her worst students came up and explained in Spanish that he had not done his homework. He had gone to bed early and had slept badly.

“What does this have to do with your homework?” Pat asked.

“I dreamed all night, Miss Jones. And my dream was in English.”

“In English?” Pat was very surprised, since he was such a bad student. She was even secretly jealous (嫉妒的). Her dream was still not in Spanish. But she encouraged her young student, “Well, tell me about your dream.”

“All the people in my dream spoke English. All the newspapers and magazines and all the TV programs were in English.”

“But that’s wonderful,” said Pat. “What did all the people say to you?”

“I am sorry, Miss Jones. That’s why I slept so badly. I didn’t understand a word they said. It was a nightmare (噩梦)”.

小题1:Pat believed that ______.

A.people can learn foreign languages in their dreams

B.she already dreamed in Spanish so she has mastered Spanish

C.one of her worst students had already mastered English

D.dreaming in a foreign language means a good command of it小题2:Pat’s student didn’t finish his home work because______.

A.the home work was too difficult

B.the student dreamed in English

C.the student didn’t sleep well

D.the student didn’t know much English小题3:The writer wrote this story ______.

A.to show us how to learn a foreign language

B.to show us how to teach a foreign language

C.to amuse us with an interesting story

D.to encourage us to travel to foreign countries小题4:From the passage we can infer that ______.

A.in Bolivia, people speak Spanish

B.Pat’s student who dreamed in English was actually good at English

C.Pat has already learned much Spanish

D.in Latin America, the newspapers and magazines are in English