如图所示，空间存在两个磁场，磁感应强度大小均为B，方向相反且垂直纸面，MN、PQ 为其边界，OO'为其对称轴。一导线折成边长为l的正方形闭合回路abcd，回路在纸面内以恒定速度v0向右运动，当运动到关于OO'对称的位置时
A．穿过回路的磁通量为零
B．回路中感应电动势大小为2Blv0
C．回路中感应电流的方向为顺时针方向
D．回路中ab边与cd边所受安培力方向相同
ABD
| 完形填空。 | |||
| Mosquitoes(蚊子)can be seen everywhere all over the world, especially in summer. And there are more than 2,500 kinds of them. __1 _likes the mosquito, but the mosquito may like you. She thinks your blood is delicious. She ? Yes , she. It’s true that the male(雄性)mosquito doesn’t bite and only the female mosquito bites because she 2 blood to lay eggs. She is always 3 things or people she wants to bite. If she likes what she finds, she will bite. But if she doesn’t like your blood, she 4 to someone else for more delicious blood. Next time a mosquito bites you, just remember you’re different from others. If the mosquito likes you, she will land on your body 5 letting you know. She bites you 6 quickly and quietly that you may feel nothing. After she bites, you will have an itch(痒)on your body because she puts something from her mouth together with your blood. By the time the itch begins, she has 7 . And then what happens? Well, after her delicious 8 ,it’s dark. The mosquito feels 9 . She just wants to find a place to have a good rest. There, on a leaf or a wall, she begins to lay eggs, 10 eggs. | |||
| ( )1.A.Everyone ( )2.A.needs ( )3.A.finding ( )4.A.will turn ( )5.A.with ( )6.A.so ( )7.A.flies away ( )8.A.breakfast ( )9.A.tiring ( )10.A.3 hundreds | B. No one B. need B. wants B. turns B. without B. such B. flew away B. dinner B. tired B. hundred of | C. Someone C. want C. looking for C. turn C. after C. very C. flown away C. lunch C. relaxing C. hundreds of | |