The tourist industry is (1)____ to be the largest industry. Before 1950 one million people traveled abroad each year but by the 1900s the figure (2)____ to 400 million every year. (3)____ large numbers of tourists, how ever, are beginning to cause problems. For example, in the Alps the skiers are destroying the mountains they came to enjoy. Even parts of Mount Everest in the Himalayas are reported to be covered (4)____ old tins, tents, and food that have been (5)____. But at a time when we have (6)____ freedom to travel than ever before, more and more people are asking how they can enjoy their holidays (7)____ causing problems by spoiling the countryside. Now there is a new holiday (8)____ called "Holidays That Don't Cost The Earth". It tells you (9)____ you can help the tourist industry by asking your travel agent the right questions (10)____ you go on holiday