so sánh 1/2^1+1/2^2+1/2^3+....+1/2^49+1/2^50 với 1

Hãy chỉ ra nhận xét đúng trong các nhận xét sau: A. Chiếc cặp sách đặt trên bàn, ta nói bàn đã thực hiện một công cơ học để nâng cặp. B. Quả nặng treo dưới lò xo, ta nói lò xo đã thực hiện một công cơ học để giữ quả nặng. C. Quả táo rơi từ trên cây xuống đất, ta nói trọng lực đã thực hiện một công cơ học. D. Cả ba nhận xét A, B, C đều sai.

VII. Put the verbs in brackets in the correct verb tense: the Present Perfect or Past Simple. 1. They (not see) the film Titanic yet. 2. Tom (call) his boss yesterday. 3. John (read) the letter from Mary already. 4. We (not begin) to learn for the test yet. 5. I (meet) Robert at the supermarket this morning. 6. Nancy (be) to Viet Nam several times. 7. I (not see) your brother yet. 8. When (your father/ give up) smoking? 9. My pen isn’t here any more. Someone (take) it already. 10. The motorbike looks clean, (you/ wash) it? XI. Choose the correct answer A, B, Cor D to fill each blank in the following passage. Mr. Brown and some (1) are on a very dirty beach now. Today they are ready to (2) the beach a clean and beautiful place again. After listening to Mr. Brown’sinstructions, they are divided into three groups. Group 1 needs to walk along the beach. Group 2 should check the sand, (3) group 3 has to check among the rocks. Garbage must be put into plastic bags, and the bags will be collected by Mr. Brown. He will take the bags to the garbage (4) . They all are (5) to work hard to refresh this area. 1. A.voluntary B.volunteers C.volunteering D.volunteer 2. A.make B.get C. do D.change 3. A.so B.but C.although D.and 4. A.dump B.yard C.area D.place 5. A.exciting B.interesting C.eager D.bored IV. Read the passage, and then choose the correct answer. Each country has many good people who take care of others. For example, some ofstudents in the United States often spend many hours as volunteers in hospitals, orphanages or homes for the elderly. They read books to the people in these places, or they just visit them and play games with them or listen to their problems. Other young volunteers go and work in the homes of people who are sick or old. They paint, clean up, or repair their houses, do the shopping. For boys who don t have fathers, there is an organization called Big Brothers. College students and other men take these boys to basketball games or on fishing trips and help them to get to know things that boys usually learn from their fathers. Each city has a number of clubs where boys and girls can go and play games. Some of these clubs show movies or hold short trips to the mountains, the beaches, museums, or other places of interest. Most of these clubs use a lot of students as volunteers because they are young enough to understand the problems of younger boys and girls. 1. What do volunteers usually do to help those who are sick or old in their homes? A.They tell them stories and sing and dance for them. B.They do shopping, and repair or clean up their houses. C. They cook, sew, and wash their clothes. D. They take them to basketball games. 2. What do they help boys whose father do not live with them? A. To learn things that boys usually learn from their fathers. B. To get to know things about their fathers. C. To get to know things that boys want from their fathers. D. To learn things about their fathers. 3. Which activity is NOT available for the students at the clubs? A. playing games B. watching films C. going to interest places D. learning photography 4. Why do they use many students as volunteers? – Because . A. they know how to do the work B. they have a lot of free time C. they can understand the problems of younger boys and girls D. they are good at playing games and learning new things 5. Where don’t students often do volunteer work? A. hospitals B. orphanages C. homes for the elderly D. clubs I. Choose the odd one out. 1.a. donate b. program c. service d. member 2. a. sick children b. volunteer c. homeless people d. disabled people 3. a. donating clothes b. cleaning streets c. providing food d. playing games 4. a. homeless b. sick c. street d. disabled 5. a. volunteer b. graffiti c. donor d. contributor

Mk hết điểm rồi,các bạn giúp mk mấy bài này với ạ Mk đã dùng hết số điểm của mk rồi, mong mn giúp lẹ ạ

: Một vận động viên điền kinh với công suất 700W đã chạy quãng đường 100m hết 10s. Một công nhân xây dựng đã sử dụng ròng rọc động để nâng một khối vật liệu nặng 650N lên cao 10m. A. Vận động viên thực hiện công lớn hơn người công nhân. B. Vận động viên thực hiện công nhỏ hơn người công nhân. C. Vận động viên thực hiện công bằng người công nhân. D. Cả A, B đều sai

Làm hết cho em nha và còn mấy bài đã làm thì check cho em

All forms of non- renewable energy sources are to a greater or lesser (1)_______ polluting , though the type of pollution varies. Coal, in common with other fossil (2)___________, produces sulphur dioxide, though ,in this respect, gas (3)___________ very favorably with coal and oil. The combustion of fossil fuels produces carbon dioxide in (4)_________ greater amounts than plant life can use. This carbon dioxide , by (5)__________in the atmosphere , may well lead to global rises (6)__________ temperature (called the “greenhouse effect”) and such rises could in time have a (7)__________ effect on climate. Nuclear fuel doesn’t emit gases into the atmosphere (8)___________used, but it produces its own highly toxic waste products. Being solid, these are easier to control than the gases emitted by fossil fuels but their presence in growing quantities is (9)____________ very dangerous indeed. All forms of fuel so far (10)__________ add to the earth’s heat load and in this way provide a long term danger to the environment. Question 1. A. degree B. extent C. extension D. amount Question 2. A. energies B. fuels C. resources D. mines Question 3. A. outgrows B. outdoes C. compares D. contrasts Question 4. A. more B. well C. far D. quite Question 5. A. raising B. collecting C. piling D. accumulating Question 6. A. in B. with C. of D. for Question 7. A. deathly B. disastrous C. unfortunate D. terrific Question 8. A. that B. however C. when D. whether Question 9. A. potentially B. merely C. possibly D. extremely Question 10. A. concerned B. complained C. proved D. mentioned

Giúp mình bài này voi mọi nguoi oi

Tính các giá trị của R1 R2 Với cùng 1 giá trị của U thì tỉ số I2/I1 là bao nhiêu

MỘT SỐ ADJ/ ADV BẤT QUI TẮC: Bad/ badly = > worse=> worst Good/ well => better => best Much/ many => most Far => farther, futher => farthest, furthest Old => older, elder => oldest, eldest Với mỗi trường hợp tính từ, trạng từ đặt 1 câu ví dụ. GIÚP MÌNH VỚI CHIỀU NAY PHẢI ĐI HỌC RỒI !