Read the following passage and choose the best answer for each blank.

Although some groups of people have always lived outdoors in tents, camping as we know it today only began to be (1) _______ about 50 years ago. The increase in the use of cars and improvements in camping equipment have allowed more people to travel longer distances into the countryside and to stay there in greater comfort.

Many campers like to be by themselves in quiet areas, (2) _____they take their tent and food and walk or cycle into the forests or the mountains. Others, preferring to be near people, drive to a public or privately-owned campsite which has up-to-date facilities, (3) _______ hot showers and swimming pools.

Whether campers are alone in the mountains or on a busy site, they should (4) _________ to leave the area clean and tidy. In the forests, they must put out any fires and keep food hidden to avoid attracting wild animals.

Although some groups of people have always lived outdoors in tents, camping as we know it today only began to be (1) _______ about 50 years ago.