Where is your yellow desk?(正确）
we aren‘t know your english teacher.
We don't know your English teacher.（改为don't know)
this is a english book.it’s on the teacher‘s desk.
this is an english book.it’s on the teacher‘s desk.(用an在English前）
his hat is on the his head.
His hat is on his head.(去掉the:the与his不能一起用）
i has a clock.it's on the wall.
I have a clock.(has改为have)