A point or period of time in the past

​When was the first video game console released?

During the 1970s. In the 1970s. Over 40 years ago. ​

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How long has Washington, D.C. been the capital of the United States?​

From the 1960 to 1970. For 10 years. ​

​We can use these words in bald to refer to something happened in the past.

A period of time that continues into the present

How long has Washington, D.C. been the capital of the USA?

Since 1800. For about 220 years.

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​We can use since and for to refer to something that has started in the past and continues until today (Present Perfect)