i remember during my time, got a few hao lians can't swim but
declare they can swim. during the test, all those who cannot swim
will have their names taken now and are not be required to
swim.
then when it's come to those few hao lians who can't swim but
declare they can swim's turn to swim, they end up struggling in the
pool. with hundred of other recruits watching from the stand.
point is if u can't swim just say so, don't hao lian, later end up
humiliating yourself. 
