课外小组的同学们做了这样一个实验:取500g水放在烧杯中,测得水的温度为20℃,

题型:计算题

问题:

课外小组的同学们做了这样一个实验:取500g水放在烧杯中,测得水的温度为20℃,然后向酒精灯倒入10g酒精,点燃酒精灯给烧杯加热,并将温度计插在水中观察水温的变化,当温度计的示数恰为70℃时,酒精灯内的酒精全部消耗完.[水的比热容为4.2×103J/(kg·℃)]

(1)请计算该实验中水吸收了多少热量?

(2)有的同学试图用水吸收的热量来计算酒精的热值,请你回答这种做法是否可以,并说明理由.

(3)若酒精的热值为3.0×107J/kg,该实验酒精灯燃烧效率是多少?

考点:能量转化效率热值热量的计算
题型:计算题

关于自体输血,下列哪项说法是错误的

A.自体输血可减少输血反应和疾病传播
B.当应用稀释式自体输血时,最好先采的先输,后采的后输
C.脾破裂出血手术时,可采用回收式自体输血
D.预存式自体输血可于术前1个月开始采血
E.胸腹腔开放性损伤超过4小时,是自体输血的禁忌

题型:计算题

阅读理解。

      English is fast becoming the language of science around the world, but what is its future among

everyday speakers? One expert points out that the percentage of native English speakers is declining

(降低) while the languages of other rapidly growing regions are being spoken by increasing numbers

of people. But English will continue to remain widespread and important.

     However, British language scholar David Graddol says English will probably drop in dominance(主

导) by the middle of this century to rank,after Chinese, about equally with Arabic, Hindi, and Urdu. "The

number of people speaking English as a first language continues to rise,but it isn't rising nearly as fast as

the numbers of many other languages around the world,simply because the main population group has

been largely in the less developed countries where languages other than English have been spoken," he

says.

     In a recent article in the journal Science, Mr. Graddol noted that three languages that are not near the

top of the list of the most widely spoken now might be there soon. These are Bengali,Tamil,and Malay,

spoken in south and southeast Asia.

     David Crystal,the author of The Cambridge Encyclo?edia of the English L徵guage, says about

1. 5 billion of the world's six billion people speak it as a second tongue compared to the 400 million

native speakers. But another expert on the English language says Mr. Graddol underestimates (低估) the

future of its dominance. "All the evidence suggests that the English language snowball is rolling down a hill

and is getting faster,but nobody quite knows what's going to happen because no language has been in this position before. " he said.

1. In David Graddol' s opinion, English will         .

A. remain widespread and important

B. be more important than any other language

C. lose its dominant position

D. die away in the near future

2. The underlined sentence in the last paragraph implies that          .

A. snowballs will roll down faster than language balls

B. the English language snowball is rolling down faster than any time in the past

C. English language will soon drop in dominance

D. more and more language users will choose English

3. How many experts express their ideas about the future of English in the passage?

A. 2.

B. 3.

C. 4.

D. 5

4. According to David Graddol,which of the folowing will possibly be one of the languages that

    will be most widely spoken?

A. Malay.  

B. Arabic.

C. Urdu.

D. German.

5. What should be the best title for the passage?

A. English Remaining the Dominant Position

B. The Future of English? Who Knows?

C. Opinions from Different Experts

D. The English Language Snowball Rolling Down

题型:计算题

在同向3车道高速公路上行车,车速高于每小时90公里、低于每小时110公里的机动车不应在哪条车道上行驶?

A.最左侧

B.中间

C.最右侧

D.任意

题型:计算题

各项公安专业工作应该结合自身工作特点开展群众工作,使群众工作成为公安专业工作的有机组成部分。( )

题型:计算题

符合单纯性肾病的临床症状

A.可有补体下降
B.非可凹性水肿
C.常伴有血压升高
D.常伴有氮质血症,可有补体下降
E.大量蛋白尿、低蛋白血症

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