问题 选择题 能说明△ABC和△A1B1C1相似的条件是( )A.AB:A1B1=AC:A1C1B.AB:A1C1=BC:A1C1且∠A=∠C1C.AB:A1B1=BC:A1C1且∠B=∠A1D.AB:A1B1=AC:A1C1且∠B=∠B1 答案 答案:C