... the exam very easily. 19. It was very cold last night, we went out for a walk. Exercises Unit 9- 10 English 12 20.It was very cold last week, we had to cancel our picnic. 21 .He was an honest man, ... him. 22 .He was an honest man, he was released from prison. 23 .The fight attendant serves dinner, I didn’t eat. 24 .The negative effect of cigarette smoking is enormous, many people still smoke. 25 .Jenny ... Unit 9- 10 English 12 BUT, SO, HOWEVER and THEREFORE Exercise 1: Add so, but, therefore, however where appropriate. 1. The wind was howling outside,_________it was warm and comfortable indoor. 2. ...
... x 2 = A 2 cos(ωt +φ 2 ). Biên độ của dao động tổng hợp làA. A = A1 + A2 + 2A1A2cos( 2 - φ1). B. A = )cos (2 122 1 2 2 2 1ϕϕ−−+ AAAAC. A =)cos (2 122 1 2 2 2 1ϕϕ−++AAAA. D. A = A1 + A2 ... động tổng hợp làA. 22 11 22 11coscossinsinϕϕϕϕϕAAAAtg++= B. 22 11 22 11coscossin-sinϕϕϕϕϕAAAAtg+=C. 22 11 22 11cosAcosAcosA+cosA=cosϕϕϕϕϕ D. 22 11 22 11cosA+cosAsinA+sinA=sinϕϕϕϕϕ81: ... u N = 4cos ( 20 9 πt - 2 9 π) (cm) B. u N = 4cos ( 20 9 πt + 2 9 π) (cm) C. u N = 4cos (40 9 πt - 2 9 π) (cm) D. u N = 4cos (40 9 πt + 2 9 π) (cm) 1 82 : Một sóng cơ...