giải giúp em bài này với ạ Một hòn bi thép khối lượng 3kg chuyển động với van tốc 1 m/s va chạm vào một hòn bi ve khối lượng 1kg đang đứng yên, sau va chạm 2 hòn bi chuyển động theo hướng cũ cuả hòn bi thép , van tốc cuả bi ve gap 3 lan van tốc cuả bi thép . tìm van tốc cuả mỗi bi sau va chạm

Một bình kín dung tích 16.8l chứa đầy khí oxi(đktc) .Người ta đốt cháy hết 3g cacbon trong bình đó, sau đó đưa 17.98g photpho vào bình để đốt tiếp a. Lượng photpho có cháy hết không b. Tính khối lượng từng sản phẩm sinh ra

Số lỗi chính tả trong một bài kiểm tra môn Anh văn của học sinh lớp 7B được cô giáo ghi lại trong bảng dưới đây. c) Tìm số lỗi trung bình trong mỗi bài kiểm tra? Giải giúp mình câu c nhe.

x^2 - 2 x - 2|x-1| + a = 0 .tìm a để pt có 4 nghiệm

The student are preparing for the coming lecture.That pleases our form teacher --->Our form teacher is

II. Choose the best word in brackets to complete the sentences.( Chọn từ đúng trong ngoặc để hoàn thành câu) (3 points) 1. I’d like some rice. I’m ............................ (hungry / thirsty / thin) 2. Are there any .......................... in the fridge ? (rice / milk / bananas) 3. I like fish very much, but she ..................... . (don’t / doesn’t / isn’t) 4. Is ........................... any milk ? (it / there / this) 5. What’s your favorite ........................, Mai? I like orange juice. (drink/water/fruit) 6. There isn’t any ........................... . (soda / oranges / apples) 7. How much .......................... do you want ? (eggs / apples / meat) 8. There ................. a lot of milk today. (is / are / be) 9. She ........................................ aerobics now. (doing / is doing / is playing) 10. A ............................. of toothpaste is 15 000d. (tube / half / bar) 11. It is .................... in the summer. (cool / cold / hot) 12. We often ............................ swimming in the summer. (play / have / go) 13. .................................... go to Hue ? (Let’s / How about / What about) 14. What about ........................ to the movies ? (go / to go / going) 15. He is going ........................................ his grandparents next week. (visit / to visit / visiting) 16. ................... doesn’t Nga want to walk? Because it’s too far. (What/When/Why) 17. Which language does she speak ? She speaks .................................................(English / England / language English) 18. Tuan is .................................................. student in my class. (fatter / fattest / the fattest) 19. What ................. Ba often do after school ? (is / do / does) 20. Ha Noi is ..................................... than Ho Chi Minh city. (small / smaller / the smallest)

I. Circle the best option for each sentence. (Choïn ñaùp aùn thích hôïp nhaát (A,B,C,or D)ñeå hoaøn thaønh caùc caâu sau .khoanh tròn ñaùp aùn mà em chọn).( 3 points) 1. Nam ______ English on Monday and Friday. A. not have B. isn’t have C. don’t have D. doesn’t have 2. We go to school at ______ in the morning. A. a quarter to seven B. seven to a quarter C. seven quarter D. a quarter seven to 3. Do children have math on Monday ? -................... A. Yes, they have B. No, they don’t C. Yes, they don’t D. No, they not have 4. Mr. Nam gets up at 7.00 and eats ______ A. a big breakfast B. the big breakfast C. big breakfast D. a breakfast big 5. Is her school ______the park ? A. in front of B. next C. in front to D. near to 6. Is this her______? A. erasers B. books C. an eraser D. eraser 7. Tan likes ______ weather because he can go swimming. A. hot B. cold C. windy D. foggy 8. Mr. Baker ______ breakfast at the moment. A. is having B. are having C. has D. have 9. My father is ..................... man. A. a old B. an old C. not young D. not very young 10. I’m tired. I’d like ..................... . A. sit down B. sitting down C. to sit down D. to sitting down 11. ______ milk does your father drink? A. How much B. How many C. How long D. How often 12 When it is hot , people often feel ______ A. hungry B. thirsty C. happy D. cold 13.The sign says “ No smoking “ . You ______ smoke . ( smoke (v): hút thuốc) A. can B. are not C. must not D. must 14 . I’m playing table tennis . _______ you like table tennis ? A.Have B .Is C. Are D. Do 15 . We have English ______ Friday A. at B. in C. to D. on 16. What time _______________you tomorrow? A. is she going to visit B. visits she C. she does visit D. she visits 17 . The boy looks thin , ______ he is strong. A. and B. for C. or D. but 18. It’s very hot. ..................... swimming? A. Why don’t we go B. Let’s go C. What about going D. all A, B& C 19. Mary and _______ would like to go to the movies. A. me B. my C. mine D. I 20. There _______ any milk in the glass. A. isn’t B. aren’t C. is D. are

Lá cờ quân đội ta vẫy trong trận Điện Biên Phủ mang tên gì ?

35.He was allowed to go out but he wanted to stay home --->Although 36.We shouldn't use plastic bags so as to have a clean environment. --->Our environment will be

Khử a mol $R_{x}$$O_{y}$ ở nhiệt độ cao cần V(lít) khí $H_{2}$. Cho toàn bộ kim loại R sau pứ tác dụng với HCl dư thu được V' lít khí $H_{2}$. So sánh V và V'