题干

关于作用力与反作用力,下列说法中正确的是(   )

A:作用力和反作用力,同时产生,同时消失,是不同性质的力

B:钢丝绳吊起货物匀速上升时,钢丝绳对货物的拉力等于货物对钢丝绳的拉力

C:石头击鸡蛋,石存蛋破,证明石头对鸡蛋的作用力大于鸡蛋对石头的反作用力

D:作用力与反作用力大小相等,方向相反,作用在同一直线上,因而它们合力为零

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答案(点此获取答案解析)

B

同类题5

阅读下列短文,从每题所给的A、B、C和D项中,选出最佳选项。

I remember, as a kid I had questioned Mom “Why doesn’t Dad love me!” Mom frowned. “Who said he doesn’t love you!” “Well, he never tells me,” I complained. “He never tells me either,”she said, smiling. “But look how hard he works to take care of us, to buy us food and clothes, and to pay for this house. That’s how your father tells us he loves us.”

After Mom died, I began visiting Dad every morning before I went to work. He was frail and moved slowly, but he always had a glass of freshly squeezed orange juice for me. Such a gesture, I knew, was as far as Dad had ever been able to go in expressing his love. Every time after drinking the juice, I walked over, hugged him and said, “I love you, Dad.” My father never told me how he felt about my hugs, and there was never any expression on his face when I gave them.

Then one morning, pressed for time, I drank my juice and made for the door. Dad stepped in front of me and asked, “Well!” “Well what?”I asked, knowing exactly what. “Well!” he repeated, looking everywhere but at me. I hugged him extra hard. It was the right time to say what I’d always wanted to. “I’m fifty years old, Dad, and you’ve never told me you love me.” My father stepped away from me. He picked up the empty juice glass, washed it and put it away. “You’ve told other people you love me.” I said, “but I’ve never heard it from you.” Dad looked very uncomfortable. I moved closer to him. “Dad, I want you to tell me you love me.” Dad took a step back, his lips pressed together. He seemed about to speak, and then shook his head. “Tell me”, I shouted. “All right I love you,” Dad finally blurted. His eyes watered, then overflowed.

I stood before him, stunned and silent. My father loved me so much that just saying so made him weep. Mom had been right. Every day of my life Dad had told me how much he loved me by what he did and what he gave. “I know, Dad,” I said. “I know.” And now at last I did.