如图所示，L1和L2为两条平行线，L1上方和L2下方都是垂直于纸面向里的磁感应强度相同的足够大匀强磁场，L1与L2之间为真空。区域A、B两点都在L2上。带电粒子（不计重力）从A点以初速度v与L2成θ=30°斜向上射出，粒子第一次斜向上穿过L2时，将该点标记为B点。下列判断正确的是
A．粒子一定带正电
B．带电粒子经过B点时的速度一 定跟在A点的速度相同
C．将带电粒子在A点时的初速度变大但方向不变，它一定不过B点
D．将带电粒子在A点时的初速度变大但方向不变，它一定经过B点
BD
| 完形填空。 |
| It was 1 birthday. He was one hundred 2 old and many people 3 to his birthday party. A newspaperman came to the party and 4 a few questions. "Many people want to know 5 you keep so healthy," the newspaperman said, "Can you tell me?" "I always get 6 at six in the morning," said the old man, "I 7 three meals a day, and never drink alcohol (酒)." " 8 ," said the newspaperman, "My uncle 9 the same, but he only lived to 10 eighty." |
| ( )1.A.Mr White ( )2.A.year ( )3.A.come ( )4.A.ask ( )5.A.what ( )6.A.up ( )7.A.eat ( )8.A.So ( )9.A.do ( )10.A.am | B.Mr White's B.years B.came B.asks B.how B.at B.eats B.Because B.does B.is | C.Mr Whites' C.a year C.comes C.asked C.which C.down C.have C.As C.did C.are | D.Mrs White D.the year D.coming D.asking D.where D.in D.has D.But D.doing D.be |