A:This is a girl.
B:This is a boy.
C:This is a teacher.
凸透镜的焦距是12cm,把点燃的蜡烛放在距凸透镜15cm处,则蜡烛通过凸透镜成()
知己知彼____ 运筹帷幄____ 出其不意____
围魏救赵____ 四面楚歌____ 草木皆兵____