题干

宇宙中,两颗靠得比较近的恒星,只受到彼此之间的万有引力作用互相绕转,称之为双星系统,设某双星系统绕其连线上的O点做匀速圆周运动,如图所示.若AO<OB,则(   )

A:星球A的向心力一定大于B的向心力

B:星球A的线速度一定大于B的线速度

C:星球A的质量一定大于B的质量

D:双星的总质量一定,双星之间的距离越大,其转动周期越大

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C,D

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  Dear Peter,

    Without knowing more about you,it's hard for me to give you some good advice.

    But firstly.I am sure that you are 1 .You said that nobody would care if you left  home.What about your2  ? And other family members ?It seems that you are very 3.You'd better go to a doctor or talk  4 your parents.They will be able to help you.

    Secondly,I'm sure there's someone else in your class who feels lonely,  5.You never know 6other people feel.Try to make friends with your classmates.And you could  7  a club to meet new people and make friends,too.

    You 8  find happiness in yourself.So my 9advice is to write a list of all the good things about yourself,learn to like yourself,and then  10  will see your confidence(信心)and like you,too. 

                                                                                                                                                                                                                   Yours,

                                                                                                                                                                                                                     Lily