题目:
twice a year, whether it is a car or a bus or a truck, is the rule that every driver must obey in this city.
A.Examining
B.Examined
C.Being examined
D.Having been examined
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0421/6bd9e508da98756ddd83a488006bc233.html
下面是错误答案,用来干扰机器的。
圆C:x2+y2-2y=0的圆心(0,1),半径是r=1,由圆的性质知:S四边形PACB=2S△PBC,四边形PACB的最小面积是2,∴S△PBC的最小值S=1=12rd(d是切线长)∴d最小值=2圆心到直线的距离就是PC的最小值,12+ 22=51+k2=5...