题干

下列关于弹力和摩擦力的说法中正确的是(   )

A:静止的物体可能受滑动摩擦力的作用

B:如果地面没有摩擦,人们将行走如飞

C:在一个接触面上有弹力就一定会有摩擦力

D:放在桌面上的课本对桌面的弹力是由于桌面发生形变而产生的

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答案(点此获取答案解析)

A

同类题2

     We always celebrated Dad’s birthday on Thanksgiving Day, even after he entered a nursing home. When we knew it might be his last birthday, the whole family decided to get together for a huge birthday celebration at the nursing home.
     Dad was a good storyteller and we were always his listeners. During a quiet moment, I announced it was now Dad's turn to listen to stories for a change. I wanted everyone to tell Dad what we loved about him. The room became quiet. Then one after another, people told stories from their hearts, while Dad listened with tears in eyes.
      Everyone seemed to have more than one story. Even the little grandchildren could't wait to tell Dad why they loved him. For a man who had been kind to so many hundreds of people in his life, here was our chance to tell him how much we love him. A few months later, at Dad's memorial service, we more fully realized what we had given to Dad that night. Those are the stories people normally tell at a funeral (葬礼) after a loved one is no longer alive to hear the words. They tell stories, full of tears. But we had given those memories to Dad in his life, and we had told them through laughter, together with hugs and joy. He had them to hold and enjoyed them from time to time in his mind during his last days and months.
     Words do matter, and they are enough. We just need to say them or to speak them publicly the ones we love. That's the ways to give back love and that's our chance to celebrate a person in his or her life.