根据对话内容，用方框中所给单词的适当形式填空，每词限用一次。

welcome    you    for    this    about

Teacher: Hi, Anna. Are  your pencils?

Anna: No, they're Bob's.

Teacher: And is this his green pen?

Anna: No, it isn't. The blue pen is his.

Teacher: What  this dictionary?

Anna: It's Helen's. And the green pen is hers, too.

Teacher: And the eraser? Is that  ?

Anna: Yes, it is.

Teacher: Thank you  your help, Anna.
Anna: You're .