My grandparents ____ going shopping. [ ]
A. is
B. are
C. am
答案：B
卫生服务需求量变动对价格变动的反应程度被称为
A．卫生需求的收入弹性
B．卫生需求的单位弹性
C．卫生需求的交叉弹性
D．卫生需求的完全弹性
E．卫生需求的价格弹性
______ is of great importance now , my teacher often reminds me ,is study.
A．It
B． As
C．What
D．Which
