When I got to classroom late, the class had already started and the teacher ______ (write) maths problems on the blackboard.

A．He is interested in English.
B．He is not interested in English.
C．He is a friend of mine.
D．He is tall and thin.

A．I often write to you.
B．I write some letters.
C．Once a month.
D．I often go to see my parents.