How to swap words in a line inside a txt file?

Question

PHP

Faced with a problem, you need to swap words inside the txt file
$baza = file("baza2.txt");///file connection
1 line
site.ru ///inside baza2.txt
2 line
site2.ru ///inside baza2. txt
echo trim($baza[0]);//show the first line of the file
echo trim($baza[1]);//show the second line of the file
How to swap
site.ru
site2.ru
It needs to become
site2.ru
site. en