1) A point or period of time in the past
과거의 어느 한 순간이나 기간
When did World War II take place?
During the 1940s. In the the 1940s. Over 70 years ago.
How long were the Beatles together?
From 1960 to 1970. For 10 years.
2) A period of time that continues into the present
현재까지 계속되고 있는 상황을 얘기할 때
How long has the United nations been in existence?
Since 1945. Since World War II ended. For about the last 70 years.
