下列计算中,错误的是( )
A:8x2+3y2=11x2y2
B:4x2﹣9x2=﹣5x2
C:5a2b﹣5ba2=0
D:3m﹣(﹣2m)=5m
某种品牌的手机经过四、五月份连续两次降价,每部售价由1000元降到了810元.则平均每月降价的百分率为( )
He ________ to escape from the prison,but were stopped by the guards.( )