who's chest size is biggest

华华这天在做科学功课.他碰到如下的一道题:

Danny measured  the  chest size of his friends when they breathed in and out.
what was Danny trying to find out?

华华略一思索,即刻写下答案:

he was trying to find out that who's chest size is biggest.





 正确答案是:
he was trying to find out if the chest size changes when breathing in and out.