原式=x-2yx-y•xyx-2y÷x+yxy
=xyx-y•xyx+y
=x2y2x2-y2.
It worried her a bit that her hair_______ grey.
A.was turning
B.has turned
C.turns
D.will turn
下列可以挂失止付的是()。
A.信用卡
B.存单
C.票据
D.以上三者都可以挂失止付