题干
-What were you doing at 8:00 last night ?
-Oh, I was busy _________ my homework
A：do
B：doing
C：did
D：done
答案(点此获取答案解析）
B
-What were you doing at 8:00 last night ?
-Oh, I was busy _________ my homework
A：do
B：doing
C：did
D：done
