Bài 2: Gọi O là tâm của hình bình hành ABCD. CMR: a/ vec BA + vec DA + vec AC = vec 0 b/ vec DA - vec DB + vec DC = vec 0 c/ overline DA - overline DB = overline OD - overline OC

1/On my return from London, i'll telephone you ->I'll give you a _________________ from London (get) 2/I don't have enough energy to play tennis ->I don't really_____________tennis (up) 3/I wish i knew the owner of this car ->I wish i___________(ehose)

1. Tom failed the test and so did John. → Neither 2. I will never forget lying on the beach in Nha Trang → I will always

1/He hasn't been back to his hometown for 10 years ->It is________ 2/It was breakfast time when Mai rang ->I was___________

Bài 2: Cho tam giác ABC có 3 góc nhọn nội tiếp đường tròn (O; R ). Các đường cao AD, BE, CF của tam giác ABC cắt nhau tại H.Gọi S là diện tích tam giác ABC. a) Chứng minh các tử giác AEHF và AEDB nội tiếp được. b) Chứng minh AB. BC. AC=4RS c) Chứng minh OC vuông góc với DE và ( DE+EF+FD). R = 2S

1/He never has enough money ->He's always___________ 2/He remember,and so did she ->He didn't_____________ 3/They had to wait for 12 hours before their flight left ->Only after a____________ 4/Their teacher is making them study hard ->They are____________ 5/Even though i admire his courage, i think he is a foolish. ->Much as___________ 6/What a surprise to see you here ->Fancy__________ 7/My mother was the most warm-heart person i have ever known ->I heve________ 9/The company presents a gold watch to each of its retiring employees ->Each___________ 10/I would do anything for you ->There is_________ 11/She didn't say a word as she left the room ->She left the room__________

1/Alice and Peter have been married for six years ->It_________________ 2/Her call to Lan lasted forty minutes ->She_______________ 3/They teach languagues ->They______________ 4/I hope to see you at Chrismas ->I'm_____________ 5/I advise you to put your money in the bank. ->You'd__________ It____________