A king had two sons and asked famous teachers to teach them.After a few 1____(year),the king fell badly ill.So he wanted to choose one of his sons as the next king,but which one would be the right person?He thought it over 2____a whole night.At last,he decided 3____(test)his sons.One day,he gave a room to each of 4____(they),“You must fill the room completely(完全地)with anything you wish.But there should be no space left and you can’t ask for advice from anyone!”