选择合适的句子补全对话，每句限用一次。

A. When did you lose it? B. Thanks for your help. C. What's the matter? D. It's Zara's. E. Is it yours?

Lucy: Kim, you look worried.

Kim: I lost my pen.

Lucy:

Kim: This morning.

Lucy: There is a red pen on the sofa.

Kim: No, it isn't.

Lucy: What colour is your pen?

Kim: It's blue.

Lucy: Look at the blue pen on the bookshelf. Is it yours?

Kim: Yes, it is.