题干
There are many volunteers ____ are helping the poor children in this area.
答案(点此获取答案解析）
who(that)
There are many volunteers ____ are helping the poor children in this area.
，则△ABC必是等腰三角形；
，则△ABC必是直角三角形；
，则△ABC必是钝角三角形；
，则△ABC必是等边三角形。
