Why do airlines charge less for a round-triptrip ticket if the traveler stays over a Saturday night?
为何如果旅客周六停留一晚，航空公司对往返机票的收费就要低？
2
Trip includes round-trip air tickets, hotel stay for two nights, and tours of the National Air and Space Museum and the office of National Geographic World.
行程包括往返机票、两晚的酒店住宿、国家航空航天博物馆和国家地理世界办公室之旅。
3
Before his trip was over, he wanted to take something away to remember his trip here.