The tourist industry is considered to be the World's largest industry. Before 1950 about one million people ___(1)___ abroad each year ___(2)___ by the 1990s the figure had ___(3)___ to over 400 million every year. ___(4)___ large numbers of tourist however, are beginning to cause problems. For example, in the Alps the skiers are destroying the mountains ___(5)___ came to enjoy. Even parts of Mount Everest in the Himalayas are reported to be covered ___(6)___ old tins, tents and food that have been ___(7)___ away. But at time when we have greater freedom to travel ___(8)___ ever before, more and more people are asking how they can enjoy their holiday ___(9)___ causing problems by spoiling the countryside. Now there is a new holiday guide called Holidays That Don't Cost the Earth. It ___(10)___ you how you can help the tourist industry by asking your travel agent or your tour operator the right questions before you go on holiday.