Hãy so sánh tình hình châu Phi và tình hình khu vực Mĩ lattinh sau chiến tránh thế giới thứ 2 đến nay

Trình bày nhận xét của em về quan hệ giữa Trung Quốc với Liên Xô và CHLB Nga từ 1950 đến nay

Giải các phương trình: 

$$\begin{gathered} \mathrm{a}, {\mathrm{x}}^4-30\mathrm{x}+31\mathrm{x}-30=0 \\ \mathrm{b}, \frac{\mathrm{x}-1009}{1010}+\frac{\mathrm{x}+3}{1011}+\frac{\mathrm{x}+2017}{1012}=6 \end{gathered}$$

tác dụng của ròng rọc cố định

Giải các phương trình sau:

a, $\frac{\mathrm{x}}{2\mathrm{x}-6}+\frac{x}{2x+2}=\frac{2x+4}{x^2-2x-3}$

$$\begin{gathered} \mathrm{b}, {\mathrm{x}}^2-5\mathrm{x}+6=0 \\ \mathrm{c}, 2{\mathrm{x}}^3+6{\mathrm{x}}^2={\mathrm{x}}^2+3\mathrm{x} \end{gathered}$$

        So sánh các tỉ số lượng giác sau :

     a) Sin $30°$ và Cos $30°$

     b) Cos $50°$và Sin $47°$

     c) tan $27°$ và Cot $27°$

     d) Cot $14°$ và tan $52°$

Cho mình hỏi vì sao trong este thì

số mol COO= số mol este;

số mol OO= số mol este vậy? Bạn nào biết giải thích giúp mình với . Mình cảm ơn!!

P/s: nCOO= nEste  mình xem ở thầy NAP. Chỉ xem bài tập thôi chứ k có trong khóa của thầy nên k hỏi ai được. 

Rewrite the sentences with the given words or phrases so that they have similar meaning to the first sentences. (1pt)

1. I like music programme best.

=> My favourite.......................................................................................................

2. We started playing football 2 hours ago.

=> We have ................................................................................................................................     

3. Our sources of energy will soon end if we don’t try to save them.

=> Unless ...................................................................................................................................

4. Do you think money is more important than any other things in the world?

=> Do you think is  ...................................................................................................................?

Read the passage and then do the tasks below.

                                                            An Eco Home

John Kangister and his wife, Kathy live an interesting house. It’s an eco home. Eco homes don’t harm the environment. They don’t use coal or oil, so they don’t produce dangerous gases.

            John and Katy’s eco home is in California, USA. It looks like a house from one of The Lord of the Rings films. Most of the house is underground. The house is very cheap to build. It has wooden walls and floors. The windows are recycled glass. There are solar panels to make electricity for the lights, DVD players, and computers. John and Kathy get water from a well and they grow vegetables in the mud on the top of the house.

            Now John and Kathy don’t want to live anywhere else. They love their home because it helps the planet greener and it looks fantastic. They think that eco homes are a great idea for everyone. 

I. Decide which statement are true (T) or false (F). (1pt)

1. Eco homes produce dangerous gases.

2. Eco homes use electricity for the household appliances.

3. The house is expensive to build.

4. The eco home has wooden floors.

5. John and Kathy grow flowers on the top of the house.

II. Answer the questions. (0.5pt)

1. Where is John’s eco home?

......................................................................................................................................................

2. What do they use to make electricity?

......................................................................................................................................................

1. Lan often (travel) to school on foot.

2. My younger brother (not be) out of the house since his parents (buy) a computer.

3. Would you like some coffee? I just (make) some.

4. Many people might (have) robots in their houses in the future.

Tìm hai số có tổng bằng 2011 và giữa chúng có tất cả 9 số chẵn