班级人数一定,每行站的人数和站的行数.
人体内的胰岛素和性激素的化学成分
— He has few friends to share his joy and sadness, _____ he?
— _________. It’s really bad for him to keep quiet all the time.
判断下面的图形是否是直角? ( )
一个正比例函数的图象经过点(2,﹣4),则这个正比例函数的表达式是____