已知圆x2+y2﹣2x﹣8y+1=0的圆心到直线ax﹣y+1=0的距离为1，则a= ．
“中国民族工业短暂的春天”出现于 A．第一次世界大战期间 B．洋务运动期间 C．甲午战争后 D．戊戌变法期间
One day 61 ant was drinking at a small stream and fell in. 62 (face) with the trouble, she tried her best to reach the side, but made no progress at all. The poor 63 (tire) ant
将两个铂电极插入氢氧化钾溶液中，向两极分别通入甲烷和氧气，即构成甲烷燃料电池，已知通入甲烷的一极，其电极反应为：CH4 + 10OH- — 8e- = CO32- + 7H
若点（a,9）在函数的图象上，则tan=的值为 （A）0 (B) (C) 1 (D)
“若使天下兼相爱，国与国不相攻……则天下治”，提出这一主张的战国时期的思想家是 A．荀子 B．庄子 C．韩非子 D．墨子
Last Tuesday, after doing all the family shopping in town, I wanted to have a rest before catching the train. So I bought a newspaper and some chocolate and went into a station coffee shop w
已知函数f(n)=且an=f(n)+f(n+1)，则a1+a2+a3…+a 100等于（ ）A.0 B.100 C.-100
，
，x2=
；