A:稻草造纸
B:使用火药
C:蚕丝织布
D:烧制陶瓷
如图,甲图怎样变成乙图:____ .
设A,B,C是△ABC三个内角,且tanA,tanB是方程3x2-5x+1=0的两个实根,那么△ABC是( )
There is a common saying in China________nothing in the world is difficult for one who sets his mind on it.