viết phương trình điều chế propan--->etan, n-butan

tính diện tích hình tam giác có đọ dài đáy là 8m và chiều cao là 27dm

Câu 1 : a) $\frac{-5}{x}$ = $\frac{-y}{8}$ = $\frac{-18}{72}$ b) Cho S = $\frac{1}{50}$ + $\frac{1}{51}$ + $\frac{1}{52}$ + ... + $\frac{1}{98}$ + $\frac{1}{99}$ Chứng tỏ rằng : S > $\frac{1}{2}$

we are let to ...... uniform to school A. wear B.wearing C. wore D.to wear

Yesterday, my school had a Sport Day. I and my friends enjoyed it very much. However, when we came back home, we didn't.....1....well. It was too.....2......, and in the afternoon, it rained heavily. Phong is my friend, he had a....3..... because the music was too loud. Some of my friends had a backache, because they played some......4....... I also had a fever, because the rainy......5...... me wet. I think I and my friends should......6....... a rest. Chọn đáp án phù hợp: ( Games ; makes ; feel ; hot ; headache ; Take )

12 A: “Congratulations, Jimmy” – B: “______.” A. Why not? B. That’s very kind of you to say so C. Nothing D. It’s OK 13 What you have said hasn’t been proved, _______? A. haven’t you B. have you C. has it D. hasn’t it 14 They have known each other ______ 5 years. A. for B. since C. yet D. ever 15 A: ________ making poster on energy saving and having them around our school? A. Let’s B. Shall we C. Why don’t we D. How about

chứng minh : x ²+y ²+z ²<2(xy+yz+xz) mới mọi x,y,z

`text(Hôm nay vác xác lên đây nhờ mn vẽ mắt cho e:))` `text(Mn đặt cho e 1 bd đi;-;)` `Huyy`

Mn vote chéo sao cho mik đc ko ạ Mik vote lại đầy đủ mãi mà vẫn ko lên nổi siêu sao hmu hmu Vẽ anime ạ

Tìm các loại từ (Danh từ, động từ, tính từ, số từ, lượng từ, chỉ từ, phó từ) có trong văn bản sau