guzhao67“to express general truth”
The key word is "general". A general truth is usually a statement that is true at all times and places:
A triangle has three sides.
1921 is in the 20th century.
25 is greater than 14.
An elephant is an animal.
Water is a liquid at room temperature.
The moon goes around the earth.
Other truths are contingent truths. They are statements of situations that could have been otherwise.
Tobacco was brought to England by Sir Walter Raleigh.
Columbus sailed across the Atlantic Ocean in 1492.
Sputnik was launched in 1958.
CJ