请选择ABCD1],P7t1T5^0O ---What _____your mum______last night?9v.b7j'i:d5s9R+v7I
---She was doing some housework.9v.b7j'i:d5s9R+v7I
A.did;do9v.b7j'i:d5s9R+v7I
B.does;do9v.b7j'i:d5s9R+v7I
C.was;doing9v.b7j'i:d5s9R+v7I
D.were;doing9v.b7j'i:d5s9R+v7I