5. I to (to write) a letter to me grandmother who (to live) in Novgorod. I (to write)to her very often.

I write a letter to my grandmother who lives in Novgorod. I write to her very often.

Объяснение: В обоих случаях используется Present Simple. Бабушка живет в Новгороде (факт), и я ей часто пишу (повторяющееся действие).