How can the Earth support life when other planets cant?

The biggest reason is water. Astronomers think maybe there really may be traces of water or ice on other planets, but Earth has an abundance, perfect for us. Also, many other planet's living conditions are not suitable. Some planets have EXTREMELY hot hot hot or coooollllddd ccccoollllddd weather that we could not live through. There is not fertile soil or animals to eat (we probably wouldn't be eating aliens :P ). And atmospheres aren't as nice, no substantial protection from the sun's rays and gravity not as strong. There are also some more detailed answers but these are mostly the main ideas why the Earth support life when other planets cant.