M和N是原来不带电的物体，它们相互摩擦后M带1.6×10－10 C的正电荷，下列判断正确的是
A．在摩擦前M和N的内部没有任何电荷
B．摩擦过程中电子从M转移到N
C．摩擦过程中质子从N转移到M
D．在摩擦过程中M和N的电荷总量不变
BD
任何物体都带有等量的正电荷与负电荷，只是对外显电中性，A错；摩擦过程中M由于失去电子而带上了正电荷，电子从M转移到N，B对；质子不能移动，C错；由电荷守恒定律可知D对；
| 请在阅读下列有关宠物的文字材料后，从方框中A、B、C、D、E五个选项中选出与题中的描述对应的选项。 | |
| ________1. Many people like animals and take them as their pets. Nowadays pet hospitals are very busy. Kind persons who love animals are needed to work in busy animal hospitals. ________2. Scientists think that pets will probably be much smaller because people in the future will be living in much smaller places. Scientists are already working on making very small farm animals. The same things might be done to make smaller cats and dogs. ________3. It's said that some day you might own a panther as a pet. Scientists might have to start turning wild animals into pets. This might be the only way to save them from dying out. ________4. What about a robot for a pet? This may sound silly, but it could become true. Robot dogs have been made to bark like real dogs. These "pets" might become more and more popular in the future. After all, robots don't lose hair or chew on things the way real pets do. ________5. Lots of people miss their pets while they are on holiday. One hotel in Minnesota has solved this problem. They lend cats to their guests. Many experts believe this idea will become more and more popular. It is very possible that in the future you will be able to order a pet, as well as room service, at a hotel.
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