题目

我国的高速铁路技术不断创出新的记录，同时旅客的安全工作更习起了人们的广泛关注假设某次列年在离车站9.5km处开始制动刹车，此时列车的速度为342km/h，列车匀减速到站并刚好停住，求： （1） 该列车进站时的加速度多大？ （2） 列车减速运动的时间为多少？ 答案：解：342km/h=95m/s根据v2=v02+2ax 可得 a=0−v022x=−9522×9500m/s2=−0.475m/s2 方向与初速度反向。 解：列车减速运动的时间为 t=0−v0a=-95-0.475s=200sOnce a circle lost a piece of its own. The circle wanted to be whole, so it went around looking for its missing piece. But because it was incomplete（不完整的）, it could only roll very slowly. It enjoyed the flowers and the sunshine along the way. It talked with worms. It found lots of different pieces, but none of them fit. So it left them all by the side of the road and kept on looking for the missing piece. Then one day the circle found a piece that fit perfectly. It put the missing piece into itself. It could be whole, with nothing missing. It was so happy and began to roll. Now that it was a perfect circle, it could roll very fast, too fast to see flowers or talk to worms. It realized how different the world was when it rolled so quickly. It felt so sad that it stopped, left its found piece by the side of the road and rolled away slowly.Sometimes we are perfect when we lost something. A man who has everything is a poor man in some ways. He will never have hopes, dreams or something better. He will never know someone is loving him or someone is giving him something he has always wanted or never had.We couldn’t be perfect, but we must be brave enough to love, strong enough to forgive, kind enough to share happiness with others and clever enough to know there is enough love around us and then we can always live a wonderful time in our lives.小题1:The circle rolled very slowly because it __________.A．spent much time talking to wormsB．wanted to enjoy the sunshineC．was looking for its missing pieceD．lost a piece of its own小题2:After it was whole again and rolled fast, the circle __________.A．felt unhappyB．could see more beautiful flowersC．could talk to any wormD．could go everywhere小题3:If a man owns everything, he’ll be __________ in some ways.A．perfectB．poorC．happyD．strong enough小题4:The story mainly tells us that __________A．nobody loves us if we give nothingB．a man who has everything is the happiestC．losing something may not be a bad thing sometimesD．we are not whole when we lose something