—Shall I get a birthday cake for Mary on my way back?—Yes,it’ll

—Shall I get a birthday cake for Mary on my way back?—Yes,it’ll be nice if you________.
A、do invite
B、invited
C、do
D、are
【正确答案】：C
【题目解析】：动词do有替代作用，以免重复。选项A=It will be nice if you get a birthday cake．do代替get a birthday cake。get是行为动词，不能用are代替。