--You should have thanked her before you left.-I meant . But when I was leaving I could

--You should have thanked her before you left.
---I meant . But when I was leaving I couldn’t find her anywhere.
A. to do
B. to
C. doing
D. doing so

A. to do(答案→)B. toC. doingD. doing so解析：本句中的meant意思是“本来打算”应该使用不定式。当与want, wish, hope, like, hate, try, have, ought, used, need, be able, be going, be glad, mean等连用时， to代替不定式结构以避免重复。

回答的不错