在下面这一短文适当的位置加上合适的表示先后顺序关系的词：Ou

题目描述

在下面这一短文适当的位置加上合适的表示先后顺序关系的词：Our manager likes traveling by train better than by airplane.Traveling by train costs less.so a lot of money can be saved.It gives him a closer look at the cities and countryside than he could get from an airplane.He finds that the passengers on the train are easy to talk with，and they are a good source of useful information;on the other hand，many airplane passengers are businessmen who keep busy with their own work while flying.Trains seem to be safer than airplanes.For these reasons，he prefers trains to airplanes unless he has to get somewhere in a hurry.