题目

短文改错Doctors tell us that holidays are not necessary. We should rest from work a week and two each year. They say we should leave our homes and goes to another part of the country. We should go away for holiday. Then after the holiday, we return home fresh but strong and ready to another year of hard work. This seems to make sense. But is it true? No exactly. Some people do not like to stay in strange hotel or strange houses. It is especially true for young children. They don’t like sudden changes in their lives. They like their homes better of all.美国著名的网球运动员罗迪克的发球时速最快可达60 m／s，这也是最新的网球发球时速的世界纪录，可以看做罗迪克发球时使质量约为60g的网球从静止开始经0.02 s后速度增加到60 m／s，则在上述过程中，网球拍对网球的作用力大小约为    （　　）A．180 NB．90 NC．360 N D．1800 N