题目

与位似，位似中心为，若，，则________． 答案：【答案】【解析】根据△ABC与△A′B′C′位似，OA′：OA=1：3，即可得B′C′：BC═1：3，进而求解．∵△ABC与△A′B′C′位似，OA′：OA=1：3，∴B′C′：BC═1：3，∵BC=2cm，∴B′C′=（cm）．故答案为：cm．(2014·安徽定远三中模拟)It made our head teacher angry ________ Wang Lin，without the ________ from the school，was absent from class for a week.A. that；permission B. which；permitC. which；permission D. that；permit