Phân số chỉ 4 bạn học sinh là:

\(\dfrac{2}{5}-\dfrac{3}{10}=\dfrac{1}{10}\)

Số học sinh lớp 6A là:

\(4:\dfrac{1}{10}=40\) (học sinh)

Đáp số: 40 học sinh

Write about 3Rs: reuse, reduce, recycle:

The 3Rs: Reduce, Reuse and Recycle. It is the only way to save the environment from getting deteriorated. We are quickly running out of space and now it is important to learn the three R’s of the environment and put it into practice.

Reduce is reducing the amount of waste you produce is the best way to help the environment. For instance buying products with minimum packaging, borrowing things which we do not use often, starting a compost bin, saving energy and water by turning are ways to reduce. To reduce the environment damage caused by cars, increase use of carpooling with friends, walking, taking the bus, or riding your bike instead of driving are the necessary steps to be taken. Same way salvage does for the environment. It helps to reduce the waste by sorting out articles of use.

Reuse is instead of throwing away articles try to find various efficient ways to reuse it. For instance, replacing few things in our day to day life like using cloth sacks in place of plastic bags, re-useable lunch bags without creating waste. Donating old clothes, toys and furniture to the needy and poor. Use writing paper on both sides etc.

Recycle is the process of changing the waste and non-useable materials into potentially useful materials. It is the key component of modern waste reduction procedure. There are some ISO standards related to recycling such as ISO 15270:2008 for plastics waste and ISO 14001:2004 for environmental management control of recycling practice. Recycling reduces the consumption of raw materials and energy usage. It also reduces air and water pollution by reducing the need of conventional waste disposal. Usage of recycled materials will help the environment to be green again.

Hence, Salvage Industry is making it more convenient to follow the rule of 3Rs by sorting the scrap.

Write about 3Rs: reuse, reduce and recycle:

Reduce, reuse and recycle (3Rs) are the three essential components of environmentally-responsible consumer behavior.

3Rs is sometimes called the waste hierarchy. Here's how that hierarchy might apply to computers:

- The concept behind the first R, reduce, is that you should limit the number of purchases that you make in the first place. So, for example, you might limit your household to a single computer.

- The concept behind the second R, reuse, is that you should reuse items as much as possible before replacing them. For example, it generally makes more environmental sense to update your computer rather than get rid of it and buy a new one. However, if you do replace your computer, you should ensure that it, or its components, are reused. Many charitable organizations welcome donations of second-hand computers.

- The concept behind the third R, recycle, is that you should ensure that items or their components are put to some new purpose as much as possible. If your computer is not fit for reuse as is, you can donate it to one of several organizations, such as StRUT (Students Recycling Used Technology), which will refurbish it or recycle its components.

Sometimes a fourth R is added to the three basic ones, generally standing for either "rethink" or "recover." Rethink is sometimes added to the front of the hierarchy, meaning that we should consider our options and think about their impact on the environment. Recover, which is the last R, refers to the practice of putting waste products to use. For example, decomposing garbage produces methane gas (one of the greenhouse gases), which some landfill sites recover and burn for energy rather than letting it dissipate.

Bác tài xế bỏ xe đi qua thui

A-Choose the word in each group which has the main stress on a different syllable from the others.

1) A. vulnerable B. integration C. intellectual D. epidemic

2) A. discriminate B. survive C. advocate D. digest

B-Choose the word in each group which has the underlined part pronounced differently from that of the others.

3) A. efficient B. suggestion C. unsure D. initiate

4) A. researched B. composed C. noticed D. stressed

5) A. daughter B. through C. thought D. laugh

Choose the phrase or clause that best completes each of the sentences below

6) The cyclist ______________ he crossed the main street.

A. looked with caution after B. was looked with caution when

C. looks with caution when D. had looked with caution before

7) _____________, we would be rich by now.

A. If we invest in the telecommunications industry

B. Unless we had investment in the telecommunications industry

C. Had we invested in the telecommunications industry

D. Did we invest in the communications industry

8) George did not study well in the class because _________________.

A. he studied bad B. he failed to study properly

C. he was not good student D. he was a badly student

9) ______________, the more he likes it.

A. The more dangerous it is B. The more it is dangerous

C. The more is it dangerous D. The more dangerous is it

10) Charlie said that ________________________________________.

A. he was thinking of going to live in Canada

B. he is thinking of going to live in Canada

C. he has thought of going to live in Canada

D. he would be thinking of going to live in Canada

B

**** cho mình nhé ! cảm ơn

Gọi 5 số tự nhiên liên tiếp là a , a+1 , a+2 , a+3 , a+4

=> a(a+1)(a+2)(a3+)(a+4) luôn chia hết cho 5

nó cũng chia hết cho 6 vì 

a(a+1)chia hết cho 2 (1)

a(a+1)(a+2)chia hết cho 3 (2)

Từ 1,2 => tích đó chia hết cho 6 vì ( 2.3)=1(**)

Từ * và ** => tích đó chia hết cho 30 vì ( 5,6 ) =1

Đổi \(132^oF\) sang \(^oC\)

\(132^oF=\left(132-32\right):1.8=55.5556^oC\left(=55\dfrac{1389}{2500}^oC\right)\)

Read the passage carefully, then choose the correct answer

The first system of communication of animals is natural. Many kinds of animals have ways of communicating with each other. And one of the most interesting examples is that of bees. These insects communicate with each other by dancing. The most important kind of dance that they do is concerned with food. They get their food from flowers, of course, from plants and trees. When a bee has found some food, it returns to the other bees and can give them three basic kinds of information about the food: which direction it is in, whether it is nearby or a long way away, and whether it is good to eat or poisonous.

The other kind of system of communication of animals is artificial. It means animals learn it; in this case, they learn from man. Several famous experiments have been carried out with chimpanzees, trying to teach them human language.

One of these experiments was done with a chimpanzee called Sarah. Sarah was taught to understand a system of symbols which represented words. The symbols were cut out of coloured plastic, and each different shape stood for a different word. For example, a red square stood for “banana”, Sarah’s favorite fruit. Soon Sarah could not only understand words, but even sentences. She could obey orders: if her human friends put down the symbols for “apple in cup”, she would put the apple in the cup. Later, she began giving the scientists orders – she was writing her own sentences, and she got upset if the scientists did not obey her. We do not yet know whether chimpanzees will ever learn to use language to communicate as freely as human beings do, but the results so far suggest that this is at least a possibility.

41) According to the passage, bees ____________________________________.

A. learn to communicate B. are born to be able to communicate

C. are the most interesting animals D. communicate with each other by flying

42) From the passage, we can conclude that bees are _____________________.

A. so selfish as to let other bees share the bad food

B. so selfish as to look for food for themselves

C. so hardworking that they dance all the time

D. so smart that they know where the food is

43) The experiment done with Sarah is an example of ____________________.

A. animals with natural system of communication

B. animals able to communicate with humans

C. animals possible to use language as humans

D. animals with a system of communication worked out by humans

44) The results of the experiment with chimpanzees show the possibility to teach animals _____.

A. how to use language freely

B. how to give orders

C. how to obey orders

D. how to understand words and sentences

45) The phrase “concerned with” is closest in meaning to ________________.

A. interested in B. responsible for C. related to D. joined to