Travelers have camped and used packs for centuries. In 1914, the word “backpack” in re

Travelers have camped and used packs for centuries. In 1914, the word “backpack” in relation to a travel pack first  __31__ (appear) in America. Now backpacking is a popular outdoor activity. Backpacking involves hiking to a camping place. Hikers always carry packs __32__ contain food and necessary items. Backpacking usually involves at least one night of outdoor camping, and can last for months if hikers add to __33__ supplies along the way. Many __34__ (mountain) regions of the world are popular among backpackers.

Backpacking is __35__ (usual) done in groups of two or more, __36__ some backpackers will go hiking alone. __37__ (Depend) on the physical stress of the trip, people of most levels of fitness can take part in backpacking.

Some individuals use backpacking __38__ a method of travel, especially in Europe. Backpacking is a cheap and fun way to __39__ most parts of Europe. Traveling backpackers appreciate the convenience. __40__ is also a way to network (建立联系) with a wide variety of individuals who meet in the course of traveling.

31．appeared　32.that / which　33.their　34.mountainous　35.usually　36.although / though

37．Depending　38.as　39.visit / see　40.Backpacking