tia tới và mặt gương vuông góc với nhau. Tính góc phản xạ

Cho tứ diện ABCD M,N lần lượt là trung điểm của AB,BC E thuộc CD mà EC=2ED -Câu hỏi : Dựng (MNE) giao ABCD(tiết diện)

Làm hộ mình với ạ MÌnh sẽ vote 5sao

hãy nhận biết các dung dịch sau a) H2SO4 , KOH, Ba( OH)2, Mg( NO3)2 b) Na2SO4, Na2CO3, Ba(NO3)2 c) AgNO3, FeSO4, KCl d) K2SO4, Ca(OH)2, HCl, H2SO4 e) Na2SO4, NaOH, NaCl, HCl

Đề bài tính nhanh 20+21+22+...+29+30 Làm hộ mình với

Giải giúp mình nha , mình cần gấp 😅😅

Rút gọn biếu thức a)3a+ √4a^2 với a<0 b)5√9a^4 - 3a^2

chọn ngẫu nhiên 1 ước nguyên dương của 15876000. Tính xác suất để tìm đc ước chia hết cho 3

VI. Rewrite the following sentences using the words given: 1. The volunteers couldn't mow the old lady's lawns because of the rain. The rain prevented...the...v.a.Luntee.r.s...fx a...mawung...the 2. Dave did his homework and then went to bed. After Dave.daAR ..haml. 0rk. Dario.ento bed. 3. It is easy for anyone to learn how to cook. Learning..,hat.v....0.o.k.. 4. It isn't polite to ask people about their salary. Asking people. 5. It costs a lot of money to study abroad. Studying 6. It takes my mother a long time to become a doctor. My mother.. 7.The police arrived too late, so the robber escaped. By the time the police arrived 8.The phone call interrupted my breakfast 1 was..... 9.Sheila went out for the evening. but first she washed her hair. Before Sheila. 10.First Trudy read the book and then she decided that she didn't like it After Trudy 11.They got to the theatre after the beginning of the play. When they 12.In the middle of our dinner, there was a knock at the door. While we 13.She didn't get anyone to repair the car for her. She repaired 14. I spent seven years at secondary school and then I went to universit After... 15.1 last saw Bob when I was in Ho Chi Minh City. I haven't seen. 16. You shouldn't eat too much meat. You'd better. 17.1 advise you to wear a coat when you go out (had better) THE END

VII. Make correct sentences from the words and phrases given. 1. You/ not/ play/ more/ computer games/ free time. ------------------------------------------------ 2. Doctor/ asking/ Mai/ questions/ about/ health problems. ----------------------------------------------------- 3. Vitamins/ play/ important/ role/ our diet. --------------------------------------------------------- 4. We/ keep/ our bodies/ warm/ avoid/ flu/ a cold. ------------------------------------------------------------- 5. Getting/ enough/ rest/ help/ you/ concentrate/ school. ---------------------------------------------