二次函数y=ax2+bx+c中,ac<0,则函数的零点个数是 [ ]
A.0个
B.1个
C.2个
D.无法确定
答案:C
You can’t expect yourself to his trust over the night because it takes time for the damage you have done to him to heal.
A.wipe out
B.turn up
C.depend on
D.win back
除灰系统中浓缩机的原理是()。
A.动分离;
B.粗细分离;
C.离心分离;
D.沉淀分离。