题目

【1】What will they do on Saturday evening?A. Go to the park. B. Go to the shop. C. Go to the concert.【2】How many tickets do they have?A. One. B. Two. C. Three.【3】Who is Mary’s favorite singer?A. Jay Chou B. Liu Huan. C. Li Na.【4】When will they meet?A. 5:00. B. 6:00. C. 7:00. 答案：【答案】【1】 C 【2】 B 【3】 A 【4】 B 【解析】W: This is Mary. Who's that?M: This is Jack. Are you free this Saturday evening?W: Yes. What's the matter?M: I have two tickets to Jay Chou's concert. Would you like to go with me?W: Certainly. I'd love to. He's my favorite singer. Thanks for your invitation. When and where shall we meet?M: Let's meet at the gate of the park at seven （2012广东中山期末）如图，A、B两点所在的圆半径分别为r1和r2，这两个圆为同心圆，圆心处有一带正电为+Q的点电荷，内外圆间的电势差为U。一电子仅在电场力作用下由A运动到B，电子经过B点时速度为v。若电子质量为m，带电量为e。求： （1）电子经过B点时的加速度大小。 （2）电子在A点时的速度大小v0。