1) The word "table" contains two vowels: A and E.

2) The smallest unit of time is known as a zeptosecond, which is equal to one trillionth of one billionth of a second.

3) The Great Rift Valley is a geological feature that stretches over 6,000 kilometers (3,700 miles) from Lebanon to Mozambique. It is known for its diverse landscapes, including deep lakes, volcanic mountains, and fertile valleys, and is considered a significant site for the study of Earth's tectonic activity.

4) The first modern Olympic marathon race was held at the 1896 Olympics in Athens and has since become one of the most iconic and challenging events in athletics.