Giúp mình gấp gấp, cmon trước ạ :)

giải hộ mình ạ.Mình đang cần gấp lắm ạ

hộ mk vs..........................

cho S=1/31+1/32+1/33+...+1/90. chứng tỏ rằng S>2/3

helppp meeeeeeeeeeeeeeeeeeeeeeeeeeeeee

Giải bất phương trình a. /2x+3/ <7 b. /2x-3/ >5

on birthday party hay in birthday party

II. Combine each sentences into a new one,using “enough” 1. The boy is intelligent .He can understand you. 2. This machine is not powerful. It cannot plough the hard soil. 3. The story is short. We can read it in one hour. 4. The film was very good. We saw it through. 5. The play was very amusing. They enjoyed it 6. This song is very simple. Everybody can sing it. 7. This book is very interesting. My son should read it. 8. We were not early. We could not see the first part of the play. 9. The children were very eager. They started playing without me. 10. This room is so big. All of them can stay in this room

vẽ mầm ngạc nhiên , phân vân hoặc ko hiểu chuyên j đag sảy ra nl : ??? hack à mn

chất nào sau đây phản ứng với dung dịch hcl sinh ra chất khí nhẹ hơn không khí, cháy trong không khí với ngọn lửa màu xanh nhạt a. caco3 b. zn c. cu d. na2o