问题 多选题

点电荷置于真空中的O点,A 、B、C三个虚线圆表示该点电荷电场中三个等势面,如图所示。已知等势面的电势φA<φB<φC,m点位于A等势面上,n点位于B等势面上。现有一电子从m点以初速度v0沿mn方向入射,在电子从m点至再次通过A等势面的过程中,以下判断正确的是 

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A.电子所受的电场力先增大后减小

B.电子所受的电场力先减小后增大

C.电子的动能先增大后减小

D.电子的动能先减小后增大

答案

AC

阅读理解

Hamsters are lovely small animals which are similar to mice,and some people 1ike to keep them as pets.They need to eat a balanced diet,or they can become very sick.That’s why hamsters should be fed healthy foods.

Most pet stores sell hamster mix.This is a combination of foods that are just right for hamsters.Some hamsters are picky eaters.They don’t eat anything they don’t like,so you have to find a hamster mix that your hamster will like.Most hamsters only eat a few tablespoons a day.You should feed them at the same time every day,or you can just keep your hamster’s bowl full.Remember to clean the bowl at least once a week.Hamsters also drink a lot of water,so be sure to keep the water supply full and fresh.

Just like people,hamsters like treats.Besides the hamster mix,you can sometimes feed your hamster seeds,nuts,and some other people food.You should never feed your hamster anything unless you are sure that it is safe for hamsters.

Feed your hamster carefully,and always take good care of your pet !

43.If hamsters don’t have a balanced diet,they will         .

A.become sick          B.drink water           C.store food                            D.feel fresh

44.What does the underlined sentence “some hamsters are picky eaters” mean?

A.They pick food with tools.          B.They mix food once a week.

C.They find their food in stores.         D.They only eat the food they like.

45.What’s the passage mainly about?

A.Where to keep hamsters.         B.When to buy hamsters.

C.What to feed hamsters.         D.Why to raise hamsters.

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