—Couldyougotobuysomesaltforme，Vince?—I'dloveto，Mum，butI...

问题详情：

—Could you go to buy some salt for me，Vince?

—I'd love to，Mum，but I ________ my homework.

A. do　  B. did　  C. am doing　  D. was doing

【回答】

 C

知识点：动词时态

题型：选择题