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 t
问题描述：
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
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