将ag过氧化钠加入到98.12g水中,完全反应后的溶液为100g,则该溶液的质量

题型:选择题

问题:

将a g 过氧化钠加入到98.12g水中,完全反应后的溶液为100g,则该溶液的质量分数为(  )

A.4%

B.2.42%

C.8%

D.1.6%

考点:溶液质量分数的计算
题型:选择题

疾病的三间分布是指:①()、②()、③()。

题型:选择题

     If English means endless new words, difficult grammar and sometimes strange pronunciation, you are

wrong. Haven't you noticed that you have become smarter since you started to learn a language?

     According to a new study by a British university, learning a second language can lead to an increase in

your brain power. Researchers found that learning other languages changes grey matter. This is the area

of the brain which processes information. It is similar to the way that exercise builds muscles.

     The study also found the effect is greater when the younger people learn a second language.

     A team led by Dr. Andrea Mechelli, from University College London, took a group of Britons who

only spoke English. They were compared with a group of "early bilinguals" who had learnt a second

language before the age of five, as well as a number of later learners.

     Scans showed that grey matter density (密度)in the brain was greater in bilinguals than in people

without a second language. But the longer a person waited before mastering a new language, the smaller

the difference is.

     "Our findings suggest that the structure of the brain is changed by the experience of learning a second

language," said the scientists.

     It means that the change itself increases the ability to learn.

     Professor Dylan Vaughan Jones of the University of Wales, has researched the link between

bilingualism and maths skills. "Having two languages gives you two windows in the world and makes the

brain more flexible (灵活的)," he said. "You are actually going beyond language and have a better

understanding of different ideas."

     The findings were matched in a study of native Italian speakers who had learned English as a second

language between the ages of 2 and 34. Reading, writing, and comprehension were all tested. The results

showed that the younger they started to learn, the better they will do it. "Studying a language means you

get an entrance to another world," explained the scientists.

1. The main subject talked about in this passage is________.

A. science on learning a second language

B. man's ability of learning a second language

C. language can help brain power

D. language learning and maths study

2. We may know from the scientific findings that________.

A. the earlier you start to learn a second language, the greater the grey matter

density is

B. there is no difference between a later second language learner and one who doesn't know a second

language

C. the experience of learning a second language has bad effect on people's brain

D. the ability of learning a second language is changing all the time

3. In the last two paragraphs,the author wants to tell us that________.

A. learning a second language is the same as studying maths

B. early learning of a second language helps you a great deal in studying other subjects

C. Italian is the best choice for you as a second language

D. you'd better choose the ages between 2 and 34 to learn a second language

题型:选择题

任何一项经济业务的发生都不会破坏会计等式的平衡关系,只会使资产和权益总额发生同增或同减的变化。( )

题型:选择题

什么是设备诊断技术?

题型:选择题

单位性状

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