now she listened thoughtfully to tharunka 's translation of their question , then answered at length : `` this one was particularly good , '' tharunka said , `` but binmuck says that they have been bringing more and more , as they get more of the serpents trained : the chinese do n't like to put goods on any one of them until it has swum the route back and forth three times without , you see , because it is such a long way ; sometimes a new serpent will change its mind and just go another way , and then all your goods are lost .