Lấy điểm vẳng cách gõ x mũ 7 theo chuẩn toán học ~.~ tặng điểm

Mấy câu lẻ giúp mik 12. He often (say) says OK when he (talk) with the guests. 13. Tom (not come) here tomorrow. 14. Listen! The bird (sing)is singing 15. Someone (cut)cut down all the trees in the garden. 16. Some animals (not eat) during winter. 19. How long you (study) in this school? 20. We (not see) them for a long time

Calli: mốc Nl: mừnk pị ghim :)?

Cho mạch điênu như hình vẽ,hddt giữa hai điểm MN=24,r=1.5ôm a hỏi giữa hai điểm AB có thể mắc bao nhiêu bóng đèn loại(6w-6v)

Hòa tan 50 gam đường vào 150 gam nước. Tính nồng độ phần trăm của dung dịch?

Giúp mình ba câu này với cần gấp lắm r, cảm ơn

1. You (receive) any letters from your parents yet? 2. How long Bob and Mary (be) married? 3. My father (not smoke) for 5 years. 4. Birds (build) their nests in the summer and (fly) to the south in winter. 5. I'm busy at the moment. I (redecorate). the sitting room. 6. I always (buy) lottery tickets but I never (win) anything. 7. I (work) for him for 10 years and he never once (say) "good morning" to me. 8. Mr Jone (be) principal of our school since last year. 9. Violets (bloom) in Spring. 10. We (not live) in England for 2 years now. 11. They (prepare) the Christmas dinner at the moment. 12. George (work) at the university so far. 13. Listen! They (learn) a new song. 14. David (repair) the TV set at the moment. He (work) at it for one hour. 15. I can't go with you because I (not finish) my homework yet. 16. John (wash) his hands now. He just (repair) the bike. 17. I (work) at my report since Monday. Now I (write) the conclusion. 18. The earth (circle) the sun once every 365 days. 19. How many times you (see) him since he went to Edinburgh? 20. Look! The boy (cry) 21. Mary (lose) her hat for 2 days. 22. He (not finish) doing it yet. 23. She (not see) him since Christmas

Calli: Lag NL: Sao dạo này hodap Lag thế

giúp mình nha mọi ngoài xin cảm ơn trc

Cho bốn lực đồng quy: F1= 9N, F2=4N, F3=9N, F4=2N. Tìm độ lớn hợp lực