Để oxi hóa hoàn toàn một kim loại M hóa trị 2 thành oxit phải dùng một lượng oxi bằng 40% lượng kim loại đã dùng.Tìm kim loại M (trình bày cách giải hộ mình gợi ý M là Ca)

Một vật nhận thêm điện dương khi

Cho ABC cân tại A. Trên tia đối của tia BC lấy điểm M, trên tia đối của CB lấy điểm N sao cho BM = CN. Từ B, hạ BE ⊥ AM (E  AM); từ C, hạ CF ⊥ AN (F  AN). a. Chứng minh: tam giác AMN cân. b. Chứng minh: BE = CF. c. Chứng minh: BME = CNF. d. Tia EB và tia FC cắt nhau tại O. Chứng minh AO là tia phân giác của góc MAN

1.THey...students yesterday. A.am B.is C.was D.were 2.They...doctors two years ago. A.am B.is c.was d.were 3.They...farmers last month. a.are b.is c.was d.were 4.We...nurses yesterday. a.are b.is c.was d.were 5.The weather...cold yesterday. a.aren't b.isn't c.wasn't d.weren't 6.I...a pupiL last week. a.aren't b.isn't c.wasn't d.weren't 7.These hats...new yesterday. a.aren't b.isn't c.wasn't d.weren't 8.My parents...teachers two years ago. a.are b.is c.was d.were 9.He..a mechanic last monday. a.aren't b.is c.wasn't d.weren't 10.....he an engineer yesterday.No,he... a.is/isn't b.are/aren't c.was/wasn't d.were/weren't 11.....it hot last week? a.am b.is c.was d.were 12.The shops...open last monday. a.am b.is c.was d.were 13.... you a teacher two years ago?Yes,i... a.is/isn't b.are/aren't c.were/wasn't d.was/weren't

đưa 1 vật nặng 100 kg lên độ cao 7 m bằng 2 cách: 1 dùng mpn dài 12m và lực kéo vật lên theo mpn là 680N.tính hiệu suất của mpn

Hãy giúp mình tìm ra đâu là hình lập phương và cho mình đặc điểm của nó đc ko ạ!!!

II. Circle the best answer: 1/I put my hat on………..protect my face from the sunlight.(for/in order/in order to/as to) 2/When somebody gets fainting, leave him or her ……….flat.(lie/lay/lying/lies) 3/Don’t give the victim any food or drink if he or she gets………(fainting/shock/burn/burns) 4/We can ease pain with ice or………..water packs.(cold/warm/hot) 5/The anti-tetanus injection is needed when somebody gets……….(burn/dog bites/shock/fainting) 6/We can stop the bleeding by using a towel cover the wound, then put……..on it.(medicine/bandage/pressure/burn). 7/People use first-aid in order to……….the victim’s pain and anxiety.(cure/treat/ease/bandage) 8/Lan tried her best in order to……..the contest.(pass/win/get/see) 9/What time…………your parents come back home tomorrow?(do/will/are/is) 10/Do your students enjoy…………to the radio?(listening/hearing/watching/seeing) 16/Could you give me a bandage, please?.........(Sure/that would be nice/good/ok) 17/………is the address of the city Museum?(Where/What/Which/Why) 18/She hasn’t finished the letter…………..(already/just/yet/never) 19/Lan’s studying hard………pass the final exam.(for/in order to/so to/as to) 20/I………….that film for five years ago.(have seen/was seeing/am seeing/saw) IV. Past Simple → Present Perfect 1.I didn't call her up 2 days ago. I haven't 2.Did you finish the test an hour ago? Have ? 3.I started playing tennis last year. I've 4.He began to use the computer when he was 19. He has 5.She didn't learn hard in 2005. She hasn't 6.The boys began playing soccer a year ago. The boys have 7.Did Dad start to work here when I was born? Has 8.Tom did not work here when I met him on the street Tom has ____________________________________________________ 9.Children began to play games at 9pm Children have_________________________________________________ 10.When did you first know her ? How long ____________________________________________________? V. Passive voice: Their homework is often done carefully. Ex: They mix the glass with certain specific chemicals. The glass is mixed with certain specific chemicals. Exercises: 1.The teacher explains the lesson carefully. 2.He takes his child to the zoo. 3.Mai does her homework carefully. 4.She washes the dishes every night 5.We clean our class every day.

a. Xác định phạm vi và kết cục của chiến tranh thế giới thứ 2. b. Sự kiện Nhật đầu hàng đồng minh tạo điều kiện cho các nước nào nổi dậy dành chính quyền.

Giúp bài 2 , 3 vs ạk . E chỉ cần cách giải thôi ạ. Mỗi bài các bạn giúp mình làm mẫu 1 câu ạk. Thanks

Câu 1: làm thành câu điều kiện 1.I've got a headache.I can't go swimming. 2.I haven't got a big house. I can't invite my friends to stay. 3. We have three children,so we won't take a year off and travel around the world. Câu 2: Viết lại câu 1: could finish the work early because he helped me. --> Thanks............. 2."Elena, I last saw Carlos in September last year" said Jane. -->Jane said................. 3.She fell asleep because of his boring speech. --->His boring speech.............