Trung bình mỗi giờ vòi nước đó chảy được số phần của bể là
( 2/15 + 1/5 ) : 2 = 1/6 bể

        ĐS :  1/6 bể

1/ Simple present tense : (Thì hiện tại đơn)

@ Đối với động từ Tobe:

(+) S + is/am/are + ......

(-) S + is/am/are + not + ......

(?) Is/Am/Are + S + ...... ?

@ Đối với động từ thường:

(+) S + V(s-es) + ......

(-) S + donot/doesnot + V + ......

(?) Do/Does + S + V + ...... ?

@ Một số từ đi kèm : often, usually, always, sometimes, never, every (day)

2/ Present progressive tense : (Thì hiện tại tiếp diễn):

(+) S + is/am/are + V-ing + ......

(-) S + is/am/are + not + V-ing + ......

(?) Is/Am/Are + S + V-ing + ...... ?

Một số từ đi kèm: now, at the moment, at present, look !, be careful ! listen !

3/ Simple past tense: (Thì quá khứ đơn :

@ Đổi với động từ Tobe:

(+) S + was/were + ......

(-) S + was/were + not + ......

(?) Was/Were + S + ...... ?

@ Đối với động từ thường:

(+) S + V2 + ......

(-) S + didnot + V + ......

(?) Did + S + V + ...... ?

Một số từ đi kèm: last, ago, yesterday

4/ Near future tense: (Thì tương lai gần):

(+) S + is/am/are + going to + V...

(-) S + is/am/are + not + going to + V...

(?) Is/Am/Are + S + going to + V ...?

Một số từ đi kèm: at a moment, tonight.

5/ Simple future tense: (Thì tương lai đơn)

(+) S + will/shall + V ...

(-) S + will/shall + not + V...

(?) Will/Shall + S + V ...?

Một số từ đi kèm: tomorrow, next, soon

6/ Present Perfect tense: (Thì hiện tại hoàn thành)

(+) S + have/has + V3 + ...

(-) S + have/has + not + V3 + ...

(?) Has/Have + S + V3 + ... ?

Một số từ đi kèm: ever, never, just, already, yet, recently,recently, since, for, several times.

7/ Past continuous: (Thì quá khứ tiếp diễn)

(+) S + was/were + V-ing + ...

(-) S + was/were + not + V-ing + ...

(?) Was/Were + S + V-ing + ...?

Một số từ đi kèm: at that time, at this time, at time, between time and time.

8/ Mối quan hệ giữa thì hiện tại hoàn thành và thì quá khứ đơn thông qua liên từ since:

Nếu hai mệnh đề được nối với nhau bởi liên từ since thì mệnh đề since thường chia ở thì quá khứ đơn, còn mệnh đề chính thường chia ở thì hiện tại hoàn thành.

Ex: Lan (learn) English since she (be) 3 years old.

=> Lan has learnt English since she was 3 years old.

9/ Mối quan hệ giữa thì quá khứ tiếp diễn và thì quá khứ đơn thông qua liên từ when:

Nếu hai mệnh đề được nối với nhau bởi liên từ when thì mệnh đề when thường chia ở thì quá khứ đơn, còn mệnh đề chính thường chia ở thì quá khứ tiếp diễn.

Ex: Lan (do) her homework when the phone (ring)

=> Lan was doing her homework when the phone rang

B . PASSIVE FORM:

C . REPORTED SPEECH:

1/ Commands – requests: (câu mệnh lệnh - yêu cầu)

S + asked/told + O + (not) to-infinitive + ...

2/ Advices : (lời khuyên)

S1 + said/told + S2 + should + bare-infinitive + ...

3/ Yes – No questions : (câu hỏi có-không)

S + asked + if/whether + S + V + ...

4/ Statements : (câu trần thuật)

@ Một số thay đổi:

D. THE PARTICIPLES:

1/ Present participle: V – ing

2/ Past participle: V3

E. Request with WOULD YOU MIND... ?:

@ Yêu cầu người khác làm việc gì : Would you mind + V-ing ... ?

@ Xin phép một cách lịch sự: Would you mind + if clause (past tense) ... ?

Do you mind + if clause (present tense) ... ?

F. CAUSATIVE FORM: (Thể sai khiến)

S + have/has + O + bare-infinitive

chữ earth (th phát âm nhẹ )

That,than,feather(=> nhấn âm mạnh)

Vì Số có 5 chữ số và số này không thay đổi khi viết các chữ số của nó theo thứ tự ngược lại Nên số đó có dạng abcba

Theo bài cho:

a+ b + c + b + a = 41

=> (a+ b) + (a + b) + c = 41

=> (a+ b) x 2 + c = 41

Vì (a + b) x 2 là số chẵn ; 41 lẻ nên c là chữ số lẻ

+) Nếu c = 9 thì (a + b) x 2 + 9 = 41 => (a + b) x 2 = 32 => a + b = 16 = 7 + 9 = 8 + 8  = 9 + 7 

=> Ta có các số: 79997; 88988; 97979

+) Nếu c = 7 thì (a + b) x 2 = 34 => a + b = 17 = 8 + 9 = 9 + 8 

=> Ta có các số: 89798; 98798

+) Nếu c = 5 thì (a + b) x 2 = 36 => a + b = 18 = 9 + 9 

=> ta có số 99599

+) Nếu c = 3 thì (a + b) x 2 = 38 => a + b = 19 => Không có chữ số a; b nào thỏa mãn

Vậy .....

:((

hix , mỏi rã rời..............

Bài 4,5 mk gửi cho bn rồi đó !!!

1.Pollution enters the Earth's atmosphere in many different ways. Most air pollution is created by people, taking the form of emissions from factories, cars, planes, or aerosol cans. Second-hand cigarette smoke is also considered air pollution. These man-made sources of pollution are called anthropogenic sources.
Some types of air pollution, such as smoke from wildfires or ash from volcanoes, occur naturally. These are called natural sources.

2.Every time we drive to school, use our heater or air conditioner, clean our windows, or even style our hair, we make choices that affect air pollution. These steps, as well as many others, are things we all can do to help reduce air pollution.

3.

Water pollution is the contamination of water bodies (e.g. lakes, rivers, oceans, aquifers and groundwater). This form of environmental degradation occurs when pollutants are directly or indirectly discharged into water bodies without adequate treatment to remove harmful compounds.

Water pollution affects the entire biosphere – plants and organisms living in these bodies of water. In almost all cases the effect is damaging not only to individual species and population, but also to the natural biological communities.

4.

If you want to help keep our waters clean, there are many things you can do to help. You can prevent water pollution of nearby rivers and lakes as well as groundwater and drinking water by following some simple guidelines in your everyday life.

5.

1. Industrial waste: Industries produce huge amount of waste which contains toxic chemicals and pollutants which can cause air pollution and damage to us and our environment. They contain pollutants such as lead, mercury, sulphur, asbestos, nitrates and many other harmful chemicals. Many industries do not have proper waste management system and drain the waste in the fresh water which goes into rivers, canals and later in to sea.

2. Sewage and waste water: The sewage and waste water that is produced by each household is chemically treated and released in to sea with fresh water. The sewage water carries harmful bacteria and chemicals that can cause serious health problems. Pathogens are known as a common water pollutant; The sewers of cities house several pathogens and thereby diseases.

3. Mining activities: Mining is the process of crushing the rock and extracting coal and other minerals from underground. These elements when extracted in the raw form contains harmful chemicals and can increase the amount of toxic elements when mixed up with water which may result in health problems.

4. Marine dumping: The garbage produce by each household in the form of paper, aluminum, rubber, glass, plastic, food if collected and deposited into the sea in some countries. These items take from 2 weeks to 200 years to decompose.

5. Accidental Oil leakage: Oil spill pose a huge concern as large amount of oil enters into the sea and does not dissolve with water; there by opens problem for local marine wildlife such as fish, birds and sea otters.

6. Burning of fossil fuels: Fossil fuels like coal and oil when burnt produce substantial amount of ash in the atmosphere. The particles which contain toxic chemicals when mixed with water vapor result in acid rain. Also, carbon dioxide is released from burning of fossil fuels which result in global warming.

7. Chemical fertilizers and pesticides: Chemical fertilizers and pesticides are used by farmers to protect crops from insects and bacterias. They are useful for the plants growth. However, when these chemicals are mixed up with water produce harmful for plants and animals.....

6.

Death of aquatic (water) animals
The main problem caused by water pollution is that it kills organisms that depend on these water bodies. Dead fish, crabs, birds and sea gulls, dolphins, and many other animals often wind up on beaches, killed by pollutants in their habitat (living environment).

Disruption of food-chains
Pollution disrupts the natural food chain as well. Pollutants such as lead and cadmium are eaten by tiny animals. Later, these animals are consumed by fish and shellfish, and the food chain continues to be disrupted at all higher levels.

Diseases
Eventually, humans are affected by this process as well. People can get diseases such as hepatitis by eating seafood that has been poisoned. In many poor nations, there is always outbreak of cholera and diseases as a result of poor drinking water treatment from contaminated waters.
Did you read about the Water contamination in Flint, Michigan, USA? Read here.

Destruction of ecosystems
Ecosystems (the interaction of living things in a place, depending on each other for life) can be severely changed or destroyed by water pollution. Many areas are now being affected by careless human pollution, and this pollution is coming back to hurt humans in many ways.

7.

Air pollution

Water pollution

Soil Pollution

Radioactive Pollution

Noise Pollution

Thermal Pollution

Light Pollution

Visual Pollution

Personal Pollution

8.

Are natural disasters increasing? Yes. Natural disasters are unpreventable occurrences that take place, ranging from mild to absolutely destructive. In recent years, it may seem as if these storms have increased from prior decades.

According to recent studies, it is true: the number of natural and geophysical disasters taking place each year is noticeably skyrocketing.

Geophysical disasters include earthquakes, volcanoes, dry rock-falls, landslides and avalanches. Climatic disasters are classified as floods, storms, tropical cyclones, local storms, heat/cold waves, droughts and wildfires.

9.When you buy a home, you want to protect it. Nothing should take away your sanctuary—not bad weather or unexplainable freak accidents.

10.Human-initiated fires are to blame for a high amount of property damage; loss of wildlife habitat and the lives of humans and animals. Some forest fires are the result of carelessness or improper habits when engaging in outdoor activities. Familiarizing yourself with appropriate forest fire preventive measures not only helps you become a more aware individual when it comes to protecting the safety and natural resources in your region, but also helps you better spread the word

Số số hạng là :

( 100 - 2 ) : 2 + 1 = 50 ( số )

Tổng trên là :

( 100 + 2 ) x 50 : 2 = 2550

           Đáp số : 2550