purpose
ˈpɜːpəs noun
4
on purpose
deliberately 故意(地),有意(地)
9
to no purpose
without any useful results [正式] 毫无效果 formal
她在他们身后叫他们,可是一点用也没有。
10
to the purpose
10. useful or helpful [过时] 有用的; 有益的,有帮助的 old-fashioned