A:页边距
B:页眉页脚
C:版心
D:装订区
已知某生产厂家的年利润y(单位:万元)与年产量x(单位:万件)的函数关系式为y=-13x3+81x-234,则使该生产厂家获得最大年利润的年产量为( ).
-- You see, it's my dream to buy __________ iPhone 6S.
-- Oh, you can ask your parents to buy __________for you.