英语：be away from get back to sp come back to sp return to sp by the lake leave sp leave for sp leave

题目

英语：be away from get back to sp come back to sp return to sp by the lake leave sp leave for sp leave sth at/in I have a toothache（该同义句） -------------------------------------------------- How many teachers are there in your school?About two __________________________数学：小明在公路上行走 速度是每小时6km 一辆车身长20m的汽车从背后驶来 并从小明身旁驶过 驶过小明身旁的时间为1.5s 则汽车的速度是?（写出过程及说明道理）

答案

英语
be away from远离某物 get back to sp/come back to sp/return to sp回到某处 by the lake 在湖边 leave for sp出发前往某地 leave sth at/in sp将某物忘在某处 I have a toothache=There is a ache in my tooth teachers
数学
追击问题,路程差为s=20m,时间t=1.5s ,小明v=6km/h(x-5/3)*1.5=20
设汽车行驶的速度是x千米/时,则
1.5/3600*x-6*1.5/3600=20/1000
解得：x=54
汽车的速度是54km/h