“苔痕上阶绿，草色入帘青”，作者刘禹锡描写了“陋室”的环境恬静、雅致．苔，属于苔藓植物．下列关于苔藓植物的描述，正确的是（ ）
点A（﹣2，3）关于原点O对称的点B（b，c），则b+c=____ ．
His ________ to become a pilot was held back by his poor eyesight.
能组成