能量在食物链的传递中递减,而农药残留在食物链中却是:
A:少量增加
B:富集
C:减少
D:不变
如果代数式-2a+3b+8的值为18,那么代数式-6a+9b+2的值等于( )
Lisa said, “The music ____ (sound) beautiful, doesn't it?”