Đáp án:
C.Không cho lợi về công
Giải thích các bước giải:
*Không có máy cơ đơn giản nào cho lợi về công ,được lợi bao nhiêu lần về lực thì thiệt bấy nhiêu lần về đường đi và ngược lại ( định luật về công)
C. Không cho lợi về công
Theo định luật về công thì không một máy cơ đơn giản nào cho ta lợi về công, lợi bao nhiêu lần về lực thì thiệt bấy nhiêu lần về quãng đường đi
Bài 4: Cho tam giác ABC vuông cân tại A. Các điểm D, E theo thứ tự di chuyển trên AB, AC sao cho BD = AE. Xác địnhvị trí điểm D, E sao cho: a/ DE có độ dài nhỏ nhất b/ Tứ giác BDEC có diện tích nhỏ nhất. Giải câu b thôi nhờ mn giúp
(1)_________the United States, many adults and children (2)_________overweight. Some people eat (3)_________food at meals. They also eat snacks between meals. Sometimes people eat healthy snacks like fruit or vegetables (4)_________many Americans eat a lot of junk food such as cookies, candy and potato chips. Eating junk food can (5)_________people gain weight. People also gain weight (6)_________they don’t get enough (7)_________. People need to walk, run, ride bicycles, or walk out in health clubs and gyms .When people exercise, they (8)_________good and have more energy. A good (9)_________ and exercise will help you (10)_________ a long and healthy life. 1. A. On B. In C. At D. from 2. A. is B. was C. were D. are 3. A. too many B. too much C. few D. plenty 4. A. but B. because C. although D. so that 5. A. get B. lead C. urge D. make 6. A. so B. however C. but D. because 7. A. exercises B. work C. exercise D. energy 8. A. become B. taste C. have D. feel 9. A. diet B. meal C. food D. health 10. A. to live B. living C. live D. to living 2. Read the passage and choose the best answer to the following questions. Bangkok, the capital of Thailand, is a city of contrasts. It is an exciting, crowded, modern city and, at the same time, a city that is full of history. The streets of Bangkok are usually noisy and have too many people. Some people are selling food; others are selling clothing, cassette tapes, flowers, or souvenirs. Visitors love the river markets, the beautiful temples and architecture, and the nightlife. Most of the year, Bangkok is hotter than any other capital city in Asia, but from December to February, the weather is not as warm and so it is much more comfortable. Actually, it’s an interesting city to visit at any time of the year. The shopping is excellent, and the prices are not as high as in many other large cities in Southeast Asia. There is always so much to do in Bangkok at anytime of the day or night – from watching Thai dancing or boxing to taking a boat trip on the river or trying some of the delicious and spicy food. And if you get tired of the city and want a quiet place, there are beautiful beaches only two hours away by bus. 1. Which phrases can you use to describe the streets of Bangkok? A. a city of contrasts B. noisy and crowded C. full of history D. excited and modern 2. What does NOT interest visitors in Bangkok? A. the shopping B. sightseeing C. the weather D. the nightlife 3. “so much to do in Bangkok” means ____. A. easy to find a job in Bangkok B. much free time C. lot of entertainment D. lot of souvenirs 4. What visitors cannot see or watch at any time of the day? A. Thai dancing B. Thai boxing C. river markets D. nightlife 5. Where is the nearest beach from Bangkok? A. only two hours B. only two hours away C. only two hours from Bangkok D. only two hours away by bus 3. Read the paragraph and fill in the gap with one suitable word: All the world knows William Shakespeare as one of the greatest poets and dramatists. He was (1).................in a small English town of Stratford-upon-Avon and (2) ..............up in a large family of eight brothers and four sisters, but many of them died very (3) ................ His father, John Shakespeare, made and sold gloves. William learned (4).....................a school in Stratford. He married very young (5)......................he was about nineteen, and soon (6).............. to London where he worked at a theater. There he began to write (7)................for the theater, his plays were good and people like (8)..................... Now Shakespeare could help his family in Stratford. He (9)........................thirty-seven plays and some books of poems. At the end of his life he came back to Stratford and (10).....................................there. C. WRITING 1. Rewrite each of the following sentences using the CAPITAL word given (do not change the capital words given). 1. They are cutting the cake with a sharp knife. (CUT) ………………………………………………………………………….. 2. I spend half an hour each day doing my homework. (TAKES) ………………………………………………………………………….. 3. Because of the bad weather, we had to stop our picnic. (FROM) ………………………………………………………………………….. 4. My mother cooks well. (A) ………………………………………………………………………….. 5. How far is it from Hanoi to Ho Chi Minh city? (DISTANCE) …………………………………………………………………………..
1. Choose the best answer to complete the following sentences 1. A: “Those girls are very good at dancing!” - B: “ ___________” A. So do I! B. I know, they are C. Yes, they do! D. They were fine, thanks 2. I occasionally miss the bus so I have to take a taxi instead. A. never B. always C. sometimes D. rarely 3. There isn’t __________ for dinner, so I have to go to the market. A. any left B. some left C. any leaning D. some leaving 4. Public ___________ in this city is quite good, and it’s not expensive. A. journey B.travel C. vehicle D. transport 5. Bicycles ___________ in the driveway. A. must not leave B. must not be leaving C. must not be left D. must not have left 6. The film was so __________. However, my father saw it from beginning to end. A. interesting B. exciting C. boring D. fascinating 7. If the weather _____________ good, I _____________ camping with classmates. A. is / go B. is / will go C. will be / go D. will be / will go 8. Find the word which has a different sound in the part underlined. A. birthday B. mouthful C. breathe D. worth 9. Rob eats a lot of fast food and he __________ on a lot of weight. A. takes B. spends C. puts D. brings 10.You are not allowed to smoke in this hall. A. forbidden B. asked C. let D. made 11. “They listen to the music with great interest” means_____________ A. They enjoy the music. B. They hate the music. C. They dislike the music . D. They never listen to that music. 12. If people turn off all electric appliances in one hour all over the world, they can save lots of ______. A. electric B. electrical C. electrician D. electricity 13. These three Rs __________ reduce, reuse and recycle. A. stand up B. stand for C. ask for D. means 14. He _________ English in this school since he _____________ here. A. has taught/moved B. taught/moved C. taught/ has moved D. has taught/has moved 15. Find the word whose main stress pattern is different from others. A. beautiful B. interesting C. environment D. difference 2. Find a mistake in each sentence and correct it. 1. She asked us learned new words immediately before we left class. A B C D 2. What were you buy at the souvenir shop yesterday? A B C D 3. My brother plays video games twice times a week. A B C D 4. He comes here with bicycle because he does not like walking. A B C D 5. There are a little fruit trees in my grandparents’ garden. A B C D 3. Fill in each gap with ONE suitable preposition. 1. It’s seven thirty and Minh is late_____________school. 2. We must clean hands _____________ having a meal. 3. He's waiting for her_____________the bus stop. 4.“How do you go to school?” - “ _____________ my father’s car.” 5. The population _____________the world is increasing. 4. Put the verbs in brackets in the right form. 1. I don’t live with my family now and we (not/see)________________each other for five years. 2. He (break) ___________ the biscuit in half and gave one piece to me. 3. Japanese (speak)_______________at the meeting tomorrow morning. 4. ______he (watch) _______the news regularly? 5. This is the second time he (lose)___________ his car key. 5. Complete the sentences with the suitable form of the words in brackets. 1. I don’t like this chair. It’s ________________(COMFORT) 2. What did you learn from your last ___________________? (DISCUSS) 3. Walking is a fun, easy and ____________________ activity. (EXPENSIVE) 4. He often drives_____________so he had an accident yesterday. (CARE) 5. I visit my granny______________a month (ONE) 6. This tree has a lot of yellow_____________ (LEAF) 7. My friend, Nga plays the piano very __________ (BEAUTY) 8. Air ___________ is a big problem in the big cities. (POLLUTE) 9. He always talks on the phone with his friend. He is very _____________ (TALK) 10. My classmate, Tim is the _____________________ player in the team. (BAD)
bài học đường đời đầu tiên của Dế Mèn đó là gì?Từ bài học của Dế Mèn,em hãy viết một đoạn văn(khoảng 100 chữ)trình bày suy nghĩ của em về tác hại của thói kiêu căng tữ phụ
V. Read the following passage and choose the item (a, b, c, or d) that best answers each of the questions about it. You can recycle many types of glass. Glass food and beverage containers can be reused and recycled many times. (In fact, only bulbs, ceramic glass, dishes, and window glass can’t be recycled.) Glass is made from soda ash, sand, and lime. If it’s thrown away, it stays there indefinitely because glass never breaks down into its original ingredients. To be recycled, glass is sorted by color, crushed into small pieces, and melted down into a liquid. Then, it is molded into new glass containers. lime (n) vôi indefinitely (adv) vĩnh viễn sort (v) phân loại 27. Which of the following can be recycled? a. glass food and beverage containers b. bulbs c. ceramic glass d. dishes and window glass 28. What does the word ‘reuse’ in line 2 mean? a. use something again b. use all of something c. throw something away d. not buying things which are overpackaged 29. Glass _______. a. is made from soda ash, sand, and lime b. stays there indefinitely if it’s thrown away c. never breaks down into its original ingredients d. all are correct 30. What does the word ‘its’ in line 5 refer to? a. glass b. soda ash c. sand d. lime 31. When people recycle glass, they_______. a. sort it by color and crush it into small pieces b. melt it into a liquid c. mould it into containers d. all are correct ngắn lắm chỉ có trắc nghiệm thôi
Bài 1: đặt 1 bình chia độ rỗng lên bàn lên bàn cân tự động thấy kim cân này chỉ vạch 125 gam . đổ vào bình chia độ 250 cm3 dầu hỏa thấy kim cân chỉ vạch 325 gam . a, xác định thể tích thủy tinh đã dùng làm bình chia độ ( biết khối lượng riêng là 2500 kg/m3) b,xác định khối và trọng lượng riêng của dầu hỏa ? Bài 2: để đưa vật giống nhau lên cao 4,5m, bạn A và B dùng mặt phẳng nghiêng có chiều dài lần lượt là 8m và 9m . hỏi : a, bạn nào dùng mặt phẳng nghiêng có độ nghiêng lớn hơn ? vì sao ? b, lực kéo của bạn nào nhỏ hơn ? tại sao? giúp mik với mình sẽ vote 5 sao cho bạn nào trả lời nhanh mà đúng :D
Mội người có bt đề về giáo thông cs tên là "giaoducatgttruonghoc.com.vn "ko ak chị cho mình và các bạn ko biết đi ạ.
Cảm nhận của em về nhân vật bé thu
Cho M=[-(x+3)-x]-[(x+2)-(x-2)] Chứng minh rằng M=-7
Vẽ cho mình một bức hình anime cute vậy đi !
Loga.vn - Cộng Đồng Luyện Thi Trực Tuyến