问题
单项选择题
汽车正在以10m/s的速度在平直的公路上前进，在它的正前方x处有一辆自行车以4m/s的速度做同方向的运动，汽车立即关闭油门做a="-"6m/s2的匀变速运动，若汽车恰好碰不上自行车，则x的大小为（）
A.9.67m
B.3.33m
C.3m
D.7m
答案
参考答案：C
搜题请搜索小程序“爱下问搜题”
汽车正在以10m/s的速度在平直的公路上前进，在它的正前方x处有一辆自行车以4m/s的速度做同方向的运动，汽车立即关闭油门做a="-"6m/s2的匀变速运动，若汽车恰好碰不上自行车，则x的大小为（）
A.9.67m
B.3.33m
C.3m
D.7m
参考答案：C
| 完形填空。 | ||||
| "So teach him to close the door", my daughter Emma responded after listening to me 1 , again, about the dog coming in from the back door, bringing with him a blast of Buffalo January 2 air. Teach a dog to close a door behind him? That has got to be a really, really 3 thing to do. But then she took a step 4 . "Come on, Kolby", she said, grabbing some treats (犒劳物) and 5 him in front of the open door. "Touch." And "touch" he did, which moved the door to a 6 position. She 7 him with a treat, smiled, looked at me, and said "see!" And I saw and became 8 . Over the last few days I have been with Kolby. Each time he comes in I bring him back to the 9 door and ask him to close. There have been 10 in the beginning, but lately more and more successes. However, there remains much work to be done. I have to get him to follow my hand signal again and again 11 he will close the door from a distance. But, I now realize, 12 you keep to the focus, the 13 will be completed. What a 14 treat to have a dog that can close the door after himself! Even more wonder can be found in the 15 I learned so clearly from both Emma and Kolby. A wish is just a wish until you decide to take 16 . Once you 17 the belief that it is "too hard", then it remains "too hard" and out of 18 . Once you want to accomplish a goal, and 19 that it is "easy", then it becomes "easy" to do what needs to be done. Just 20 doing it. | ||||
|