题干
—Now that you like computers very much, isn’t it a good idea to get ______?
—Well, I’d like to but I can’t afford that expensive a computer at present.
A：one
B：them
C：it
D：that
答案(点此获取答案解析）
A
，则目标函数z = 3x –4y的最小值为（ ）
