tại sao về mùa đông khi trời lạnh dưới một mức nào đó ta nhìn thấy hơi thở của mình tạo thành 1 luồng trắng đục trong không khí mà ta thường nói rằng thở ra khói? Tại sao hiện tượng này càng rõ khi ta thở ra bằng miệng thay vì bằng mũi Giải thích từng bước hộ mình với mình hết điểm rồi nên mong các bạn thông cảm

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I. Put the verbs in correct tense: 1. I (be)___Tam . I ( be)_________a student. These (be)__________my brother and sister. 2. Who (be)______________they? They (be)___________Minh and Hoang. 3. How many people ( there/ be)________________-__ in your family? There (be)________four. 4. Four people (be)___________in the yard. They (be)___________students. 5. Her brother (be)___________twenty and her sister (be)___________twenty four. 6. What ___________you (do)___________? I (be)____________a doctor. 7. What___________he (do)____________? He (be)__________an engineer. 8. What _____________Nam and Lan (do)___________? They (be)___________students. 9. How many floors ________your school (have)__________? It (have)__________two floors. 10. My brother and I (be)____________students. 11.Ba ( be ) ……my friend. He (live)………In Ha Noi with his mother, father and elder sister.His parents(be)……teachers.Ba(go)……to Quang Trung school. 12.Nam (like)…sports. He( swim)…,he (play)…. soccer and he (play)…badminton. 13.We (go)……….to school everyday. 14.She(not drink)………………coffee. She (drink)………….. cocacola. 15.It (be)……….often hot in the summer. 16.What………you………(do) every morning ? 17.The earth (circle)……….. the sun once every 365 days. 18. I (see¬)………….her very often. 19.Most rivers (flow)………. into the sea 20.Vegetarians (not eat)………………meat. 21.Bees (make)……………..honey. 22.Where………..Martin……….(come)from? 23.The sun (rise)………..in the east and(set )…………in the west. II. Give the correct form of the verb in bracket 1- Miss White's students ( not be) big. 2- Lan's brothers (be) doctor. 3- Nam's father (be) Mai's teacher. 4- Mai and Hoa (not be). Mr Tam's students 5. I(be not) a student. I (be) a nurse. 6. They (be not) her father and mother. 7. The doctors (be not) in the room. 8. Their classroom (be not) on the fourth floor. 9. Hung’s house (be not) on Tran Phu street. 10. These ( be not) her father’s books 11. Lan and Huong(be not) in class 7A. Their teacher ( be not) Mr Tien. 12. You(be) a nurse? 13. They (be) in the classroom? 14. Your house (be) in Da Mai? 15. It (be) 10 o’clock now? 16. These schoolbags (be) Lan’s and Hoa’s? 17. Huong’s classroom (be) on the second floor?