Напишите по предложению на каждое время: present simpl,present continuous,present perfect,past simpl,future simpl

This girl often writes letters to her boy-friend.(present Simple)
Their children are reading a book in the park now.(Present Continuous)
I have been studying.(Present Perfect)
I was in Lomdon last year.(Past Simpl)
They will finally see mistakes in their program.(Future Simple)