A:物体有一定的初速度,且受到一个始终和初速度垂直的恒力作用
B:物体有一定的初速度,且受到一个大小不变,方向变化的力的作用
C:物体有一定的初速度,且受到一个方向始终指向圆心的力的作用
D:物体有一定的初速度,且受到一个大小不变方向始终跟速度垂直的力的作用
Do you know about the U.K.? London is the capital city. Its flag is red, white and blue.They speak English. Big Ben is very famous. Kings and queens live in palaces. I have an uncle. He lives in London.He says, "London is clean and beautiful."He is a teacher. He works from Monday to Friday.On Saturdays and Sundays, he likes to play football and go for a walk. I want to go to the U.K. Because I want to see Buckingham Palace.
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