Giúp mik câu 3 vs ạ cần gấp hứa cho ctljn

EM cần anh chị giải dùm nhanh nhất với ạ ,em cảm ơn !!!

Tính nhanh A=2/1.3+2/3.5+...+2/99.101

giúp mình vs ạ, mĩnh sẽ vote 5* và ctlhn

241. Ba said, "Why don't we stop eating chicken to avoid being infected with bird -Ba suggested that chicken shouldn't... 242 Let's break for lunch," -John auggested that. 230. Would you like to have lunch with me on Sunday?" --Lan invited mo 231. Would you like a cup of tea?" Jana offered John. 232 Why don't we discuss it over a coffee? -Tom suggested.

helpppppppppppppppppppppppppppp

Exercise 5: Put the verbs in brackets into the past simple or the present perfect I (1) _____________ (be) a ski instructor for many years now. I (2) _______ (take up) the sport when I (3) _________ (be) at school. I still remember the first time I (4) ______ (try) to ski. I (5) _________ (slip) on the ice and (6) ________ (break) my ankle. Thankfully, I (7) _______ (not/ have) a serious accident since then. Last year, I (8) ______ (try) ice-skating for the very first time. I (9) ________ (slip) on the ice rink a couple of times since then but I (10) ________ (not/ break) anything. Two years ago, I (11) _______ (take) snowboarding lessons. I (12) _______ (not/ like) it because I (13) ____ (find) it a little dangerous. I (14) ________ (not/ play) ice - hockey yet. There’s a game tomorrow. I can’t wait to go!

Tính giá trị của A A=1-2+3-4+...+99-100

Cho hình bình hành `ABCD` có `M`, `N` thoả mãn `vec{NC}+vec{ND}=vec{0}` và `vec{MA}+1/2vec{MB}=vec{0}`. `G` là trọng tâm `triangleBMN`. Chứng minh: a) `vec{AN}=vec{AC}-1/2vec{AB}` b) `vec{AG}=1/3vec{AC}+5/18vec{AB}`

Hợp chất B ở thể khí Có công thức RO2. Biết rằng khối lượng của 5,6 lít khí (đktc) B là 16g . Hãy xác định công thức của B