My uncle's reviews on the four great classical Chinese novels may be published _____ the summer of 2021.( )
A.inB.onC.atD.for
This blue pen is .
Look! Some ______ are in the school.
--Are those the ______ books? -- No, they are ______ books.
--______ are they? --They are my ______.
These two are on the chair.