Time Expressions for the Past

Last—last night, last Tuesday, last week, last month, last year, last summer

Yesterday—yesterday, yesterday morning, the day before yesterday

Ago—six years ago, two days ago, a week ago, five hours ago, ten minutes ago 

They didn’t go to school when they were four years old.

When I was a child, I used to play with my toys all day.

in 1998,

in the 20th century,

on May 25th 2000,

on Monday,

this morning,

at 6 a.m.