of the students in our school are boys.

Who’s that boy reading in the garden? Is it David?— It ____________ be David. I saw him in the classroom just now．

Please______ your football shoes ,David . Your room is very untidy .

______ your sister ______ in Greener China for a long time?—Yes.She joined it five years ago.

Is this your book, Alice? —Yes, it is ____ book. Thank you.