Enlist (取得帮助) the assistance of a travel agent. Consider letting him or her double-check all the details, make suggestions, and then handle the actual reservations. A good one can sometimes work out a lower fare and will know some tricks of the trade, such as booking you in a sleeping car that’s right next to the diner so you won’t have to walk through several cars on a moving train three times a day for your meals. ——What does the word “one” mean in the Paragraph 3?