cho tam giác nhọn ABC , H là trực tâm, qua B và C lần lược kẻ các đường vuông góc với AB,AC , chúng cắt nhau tại O. chứng minh HB song song CD ; chứng minh HD song song BD. các bạn nhớ vẽ hình nha

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chia động từ ạ. giúp mình với Complete the following sentences using one correct verb form. 1. How many hours did you let your children (watch)…………. TV yesterday? 2. I don’t know where my teacher of English (come)……………from. 3. The child’s classification activities (design)………….. by the teacher. 4. There (be)………..only thirty children in this class at the beginning of the school year. 5. If they (not know ) ................... the written language, children ( not / able to read) ...................... well 6. The children had nightmares because of (watch)...............a horror film. 7. The novel “Frankenstein” (write).....................by Mary Shelly. 8. A lot of mosquitoes (bite)................my little son last night. 9. I ..................... ( not listen ) to my teacher and I failed the exam. 10. The child (win / not) .................. the game if he (know / not) ................... the rules.. 11. If the child (cry)..................., she (give) ................... him a toy. 12. My child’s toy car was stolen, so I have to (get)………….another one for him. 13. It takes Mss. Lan half an hour (clean)……….. the classroom everyday. 14. When you (start)…………..your job? - In 2009 15. What do you like teaching more, singing or (tell)……………. stories? 16. How long do you let your children (take)…………. nap a day? 17. I prefer (teach).............. children aged 5 class. 18. Son (have to) ...............wash up after meals when he was at the age of ten. 19. He (talk) ................... to her if you (want / not) ................... to do it. 20. The children have just been to toilets. They (wash)………… hands at the washbasins.