—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
—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
C