Đặc điểm của tia tử ngoại A.Tác dụng mạnh,có khả năng xuyên thấu. B.Xuyên qua lớp mô và có tác dụng kéo dài. C.Không có khả năng xuyên sâu. D.Có khả năng xuyên sâu.

Exercise 3. Rewrite each of the following sentences with present participle or perfect participle. 9.The woman was invited to the party. She was happy. 10. The young man was tired of sleeping on the floor. He bought a new real bed. 11. The window was broken in last night’s storm. It has now been repaired 12. The man found the door unlocked. He went into the room. ai giúp tui mấy câu này tui cho đủ 5 sao <3

Viết PTHH theo chuyển đổi sau C ---->CO2 ------> CaCO3 -------> CO2

Câu 1: a/Viết công thức tỉ khối của khí A so với khí A, tỉ khối của khí A so với không khí. b/ Cho các khí CH4, O2, CO2, N2O, H2. Khí nào nhẹ hơn không khí. Câu 2: a/ Hệ thống tính chất hóa học của H2 (có PTHH minh họa cho mỗi tính chất, và điều kiện xảy ra phản ứng). b/ Trình bày cách điều chế khí Hidro trong phòng thí nghiệm: - Hóa chất - PTHH - Cách thu khí Câu 3: Cho m gam kẽm tác dụng đủ với dung dịch chứa a gam axit clohidirc (HCl), sau phản ứng thu được 6,72 lít khí H2 (đktc). Tính m, a?

Giải các phương trình sau c)( 3x -1) phần 3 (x + 2) phần2 - 2x^2 + 1/ 2= 11/ 2 d) x - 1 /2 + x - 1 /3 - x-1 / 6 =2

Mọi người giúp em với ạ Em cám ơn nhiều

1/ She _________ the house last weekend. * A. was cleaning B. cleans C. clean D. cleaned 2. I _________ a little English before I went to Singapore. * A. study B. had studied C. had study D. have studied 3/ Why _________ you absent yesterday ? * A. did B. are C. was D. were A. meet B. met C. did meet D. were meet 5/ When he _________ , she was cleaning her room. * A. arrives B. arrived C. is arriving D. was arriving 6/ Last night, the police _________ me on my way home. * A. is stopping B. stopped C. stops D. was stopping 7/ Mai and Huong _________ their last summer vacation on the farm. * A. don’t spend B. aren’t spent C. didn’t spend D. weren’t spent 8/ What _________ you _________ last night? * A. do / do B. did / do C. do / did D. were / doing 9/ Before I went to bed, I _________ my teeth. * A. have brushed B. had brushed C. brushed D. brush 10/ The floor _________ with a sheet of plastic five days ago. * A. covered B. was covering C. was covered D. is covered 11/ Before my mother came home, my brother _________ food on the table. * A. had prepared B. have prepared C. prepared D. had prepare 12/ Phong _________ with his friends last month. * A. went fish B. went fished C. went fishing D. went to fish 13/ I watched movie after I _________ my homework. * A. have completed B. had complete C. had completed D. completed 14/ She _________ breakfast at 8.30 yesterday morning. * A. had B. is having C. was having D. has 15/ When I got up, it _________. * A. rains B. rained C. is raining D. was raining 16/ Mrs. Thu _________ the newspaper while her husband was watching T.V. * A. was reading B. is reading C. reads D. read 17/ Mr. Quang fell over while he _________ basketball. * A. was playing B. is playing C. played D. plays 18/ When I came home, everybody _________ the television. * A. watched B. were watching C. was watching D. is watching 19/ My father _________ out when my sister arrived at the zoo . * A. goes B. have gone C. has gone D. had gone 20/ Alice _________ a Vietnamese person until he met Nam. * A. had never met B. have never met C. never met D. never have met mình cần gấp nha thank

Mn giúp mk làm phần 2 la mã nhé mk cảm ơn

giúp mình nhé để mình còn nộp cho cô với ạ

một cửa hàng đã bán 14m vải đỏ . cửa hàng còn lại số vải đó gấp 4 lần số vải do đã bán . hỏi trước khi bán cửa hàng có bao nhiêu m vải do