(It )is Helen's.The blue pen (is) his.Ask (the
(It )is Helen's.
The blue pen (is) his.
Ask (the teacher) for it.
How do you spell (it)?
Is (that) a green pen?
They're (on the sofa).
Where's (the schoolbag)?
I (don't konw).
I konw (Tom).
They are (on the desk).
括号里是什么句子成分?最好有理由.