题干

在验证力的平行四边形定则的实验中,使b弹簧秤按图所示位置开始顺时针缓慢转动,在这过程中保持O点位置不变和a弹簧秤的拉伸方向不变,则在整个过程中关ab弹簧秤的读数变化是(    )

A:a增大,b减小

B:a减小,b增大

C:a减小,b先增大后减小

D:a减小,b先减小后增大

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D

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    When I was a little girl, I remember that when my dad was repairing something,he would ask me to hold the hammer,so we would have time for a conversation with each other.I never saw my dad drinking or taking a night out. All he did after work was taking care of his family.

    I grew up and left home for college and since then,my dad had been calling me every Sunday morning.And when I bought a house several years later,my dad painted it by himself in the fierce summer heat.All he asked was to talk to him,but I was to busy in those days.

    Four years ago,my dad visited me.He spent many hours putting together a swing for my daughter.He asked me to have a talk with him,but I had to prepare for a trip that weekend.

    One Sunday morning we had a telephone talk as usual.I noticed that my dad had forgotten some things that we discussed lately.I was in a hurry,so our conversation was short.Several hours later that day I received a call.My father was in the hospital.Immediately I bought a plane ticket and on my way I was thinking about all the occasions I missed to have a talk with my dad.By the time I arrived at the hospital,my father had passed away.Now it was he who did not have time for a conversation with me.I realized how little I knew about my dad,his deepest thoughts and his dreams.

    After his death I learned much more about him and even more about myself.All he ever wanted was my time. And now he has all my attention every single day.