I watched TV an hour ago
I will watch TV on Wednesday
I am watching TV at the moment
My sister studied music three weeks ago
My sister will study music next month
my sister is studying music at present
Pete learned an English poem by heart yesterday
Pete will learn an English poem by heart in a week
Pete is learning an English poem by heart now
My granny wrote a letter to her friend in 2016
My granny will write a letter to her friend tomorrow
My granny is writing a letter to her friend at the moment