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许多同学都看过杂技演员表演的“水流星”，一根细绳系着盛水的杯子，演员抡起绳子，杯子就做圆周运动．不管演员怎样抡，水都不从杯里洒出．甚至杯子在竖直面内运动到最高点时，已经杯口朝下，水也不会从杯子里洒出来．演员的精采表演，每每博得观众的热烈掌声，杯子在竖直面内做匀速圆周运动的过程，则下列关于其中的一只杯子说法正确的是 A．受平衡力作用           B．重力势能保持不变 C．机械能在不断改变       D．它的动“Do you want to come with me?” Kelly asked her brother, “I’m going to meet some friends at the bike course. We’re going to practice for the race next week.” “No, thanks,” Marcus replied. He was sporty. Most sports were a piece of cake to him. He knew he would win.When the race day finally arrived, Marcus and Kelly rode their bikes to the Oak Park Trails with their parents.“My stomach feels like I ate some butterflies,” Kelly told Marcus when they saw the crowd of kids.“Don’t worry. You’ll do fine,” Marcus said.The starter shouted “Go”. Marcus quickly rode to the front. A few minutes later there wasn’t anyone ahead of him! Marcus raced along the trail. Time passed, and he was surprised that the course was so long.His tired legs felt like they weighed a hundred pounds. All at once, a flash of color caught his eye. There was a line of bike riders ahead him! “How could this be?” Marcus said to himself as he pushed forward. “I must have taken a wrong turn,” he thought Marcus tried hard, but he realized his speed wouldn’t be enough this time and bike course was just as important.After the race, Marcus saw his sister at the finish line, and he rode over to her. “Wow, you must have done a good job in the race. What place did you get?” Marcus asked Kelly.“I came in third place. Mom and Dad said I would even receive a medal(奖牌)!” Kelly answered excitedly.“That’s great! I came in ninth place. But I’ll do better next year because I’ll be smart enough to practice the course with you,” Marcus replied with a smile.1.When Kelly said “My stomach feels like I ate some butterflies,” we know that she felt ______.A. excited B. surprised C. nervous D. angry2.What does the underline word “this” refer to?A. Marcus felt very tired. B. Marcus took a wrong turn.C. Some bike riders lost their way. D. Some bike riders were in front of Marcus.3.What would probably happen the following year?A. Marcus would prepare for the race.B. Marcus would receive a medal in the race.C. Marcus would train his sister on the course.D. Marcus would ask his friends to take part in the race. 1.C 2.D 3.A 【解析】文章大意：本文讲述了马库斯的妹妹Kelly邀请马库斯和她一起去上自行车课，好参加下周的比赛，但马库斯认为运动对他来说小菜一碟，他认为他会赢。结果他得了第九名，而他妹妹得了第三名。最后他决定和他妹妹一起去上自行车课，好为明年的比赛做准备。 1.细节理解题。根据下文“Don’t worry. You’ll do fine,” Marcus sai...