Cho hình bình hành ABCD. Gọi E, F lần lượt là trung điểm của AB, CD. a, cmr AF // EC b, cmr ED = BF c, gọi O là giao điểm của AC và BD.CMR E,O,F thẳng hàng

Giúp em vớii. Em cảm ơn CONSERVING THE WORLD’S NATURAL RESOURCES In the decade of the 1970s, the United Nations organized several important meeting on the human environment to study a very serious problem. We humans are destroying the world around us. We are using up all of our natural resources. We must learn to conserve them, or life will be very bad for our children and our grandchildren. There are several major parts to this problem. 1. Population. Most problems of the environment come from population growth. In 1700 there were 1.6 billion, in 1950 2.5 billion, and in 1980 4.4 billion. In the year 2000 there will be 6.3 billion. More people need more water, more food, more wood, and more petroleum. 2. Distribution. Scientists say there is enough water in the world for everyone, but some countries have a lot of water and some have only a little. Some areas get all their rain during one season. The rest of the year is dry. There are huge forests in the Amazon area of Brazil. In other parts of the world there is only desert. 3. Petroleum. We are using up the world’s petroleum. We use it in our cars and to heat our building in winter. Farmers use petrochemicals to make the soil rich. They use them to kill insects that eat plants. These chemicals go into rivers and lakes and kill the fish there. Thousands of people also die from these chemicals every year. Chemicals also go into the air and pollute it. Winds carry this polluted air to other countries and other continents. 4. Poverty. Poor farmers use the same land over and over. The land needs a rest so it will be better next year. However, the farmers must have food this year. Poor people cut down trees for fire wood. In some areas, when the trees are gone, the land become desert. However, people need wood to cook their food now. Poor people cannot save the environment for the future. We now have the information and the ability to solve these huge problems. However, this is not a problem for one country or one area of the world. It is a problem for all humans. The people and the nations of the world must work together to conserve the world’s resources. No one controls the future, but we can help make it. 1. We are using up all of our ………………… A. oceans B. homes C. farms D. natural resources 2. Most environmental problems come from …………………. A. forests B. population growth C. too much rain D. poor distribution 3. Good distribution means …………………. A. having things in the right places at the right time B. cutting down forests and selling them to other countries C. building water systems to carry water to farms D. conserving our natural resources 4. Poor farmers don’t give their land a rest because ………………… A. They don’t have petrochemicals to kill insects. B. They don’t have enough land to let some of it rest each year. C. They need more water. D. They need firewood 5. Which one of these statements is not true? A. People must work together to save the environment B. We have the ability to solve environmental problems C. We control the future. D We help make the future.

M.n mún dịch nhiêu câu cx đc ạ Tại em hết điểm rồi nên là em sẽ chấm cho TLNH ạ Mong ac giúp đỡ

Giúp em em cần gấp .................................

do you think money is..... (important) good healthy

Giúp mình bài này với ạ, mình đang cần gấp

a) x^2 - 7 b)x^4 - 3 c)x^2 - 2 √13x^2 +13 d)x^2 - 16 e)x - 81 f)x^2 + 2 √5 x+5

Một hỗn hợp X gồm etanol (C2H6O) và glixerol (C3H8O3) có tỉ lệ khối lượng tương ứng là 1 : 4. a) Tính số mol của mỗi chất có trong 103,5 g hỗn hợp X. b) Đem hòa tan 34,5 g hỗn hợp X vào cốc nước thì được 58,8 g dung dịch lỏng. Tính số mol mỗi chất (C2H6O, C3H8O3, H2O) có trong cốc

Cho số tự nhiên A gồm 2n chữ số 1 (n thuộc N*), số tự nhiên B gồm n chữ số 2. Chứng minh rằng hiệu A- B là số chính phương.

Ý nghĩa lịch sử và nguyên nhân thắng lợi của cuộc kháng chiến chống pháp (1945-1954).