题目

小船过河时，船头偏向上游与水流方向成α角，船相对静水的速度为v，其航线恰好垂直于河岸。现水流速度稍有增大，为保持航线不变，且准时到达对岸，下列措施中可行的是（ ）A.增大α角，增大船速v B.减小α角，增大船速vC.减小α角，保持船速v不变 D.增大α角，保持船速v不变 答案：【答案】A【解析】由题意可知，船相对静水的速度为v ，其航线恰好垂直于河岸。因为合速度方向指向河岸且大小不变，如图可得当水流速度增大时，可增大船速v，同时增大α角，故A符合题意，BCD不符合题意。故选A。假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。错误涉及一个单词的增加、删除或修改。增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。删除：把多余的词用斜线（\）划掉。修改：在错的词下划一横线，并在该词下面写出修改后的词。注意：1.每处错误及其修改均仅限一词；2.只允许修改10处，多者（从第11处起）不计分。My school life is very interesting but meaningful. I usually get up at a quarter past six. After I wash his face, I read English for about half an hour. I think what it is a good habit. I always go to school by bike, to eat lunch at school and have a short sleep on the classroom. In the afternoon school is over at 5 o’clock. After school, I often play basketball or do some other sport on the playground happy. I went home at about five forty. Have had supper, I watch TV for while, and then I do my homework. I go to bed at about 9:30.