The boy writes on the black board просклонять предложение в разных временах по .

Past simple:
the boy wrote on the black board.
past continuous:
the boy was writing on the black board.
past perfect:
the boy had written on the black board.

present continuos:
the boy is writing on the black board.
present perfect:
the boy has writtwn on the black board.

future simple:
the boy will write on the black board.
future continuos:
the boy will be writing on the black board.
future perfect:
the boy will have written on the black board.

вроде всё..