题干

如图所示,在均匀杠杆的A处挂3个钩码,B处挂2个钩码,杠杆恰好在水平位置平衡,已知每个钩码的质量均为50g,若在A,B两处各加1个钩码,那么杠杆(   )

A:右边向下倾斜

B:左边向下倾斜

C:仍保持水平位置平衡

D:无法确定杠杆是否平衡

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答案(点此获取答案解析)

A

同类题5

读短文,从每题所给选项中选出可以填入空白处的最佳选项。

    Ever since I was a child, my mouth has caused me trouble. I'm not a bad person; I have a 1 time learning when to keep my mouth closed.

    My mom has told me again and again, "Robert, your constant bad words are hurting me. If you 2 to be this rude, you will get into big trouble."

    It's been a problem at school several times too when teachers have told me something I didn't want to hear. I used to feel it was my duty(职责) to 3 myself.

    One day in English class I began working on my homework until I heard a classmate 4 behind me. It was Nathaniel, who liked doing that as usual.

    At first, I said very 5, "Nathaniel, would you please be quiet?"

    However, Nathaniel continued talking to himself. I quickly 6 "Nathaniel, shut up(闭嘴)!"

    For the next five minutes, we threw hurtful(伤感情的) words back and forth at each other.

    "At least I don't have an ugly lazy eye like you!" I shouted.

    I knew this would make him 7. It would hurt his feelings and shut him up.

    What I said filled him with anger. He tried to 8 over my seat and catch me as he shouted, "That's it! That's it!"

    9 at his reaction(反应), I sat back in my seat. I had never seen Nathaniel act like this before.

    Later on, we were taken to the principal's office. There, Mr. Black, our English teacher, told us to 10 the matter. It wasn't until then that I finally found that 11 I hurt someone physically(身体上), the wounds eventually heal(愈合). But when I hurt them with my 12, sometimes the pain (痛苦) never goes away.

    At the end of the discussion, I said 13 to Nathaniel.

    When I went back to my room, I spent some time praying(祈祷). I began to 14 how often what I said hurt others. But I believe that as I keep praying and asking God to help me, he'll tell me when to keep my 15 closed.