 Although xenon is rare and relatively expensive to extract from the Earth 's atmosphere , it has a number of applications . 
 Although xenon <a href='drop_aux' title='1'><mark>is</mark></a>rare and relatively expensive to extract from the Earth <a href='null_genetive' title='2'><mark>'s</mark></a>atmosphere , it <a href='got' title='3'><mark>has</mark></a> a number of applications . 
Although xenon rare and relatively expensive to extract from da Earth  atmosphere , it got a number of applications .