阅读理解。 Tourism was not always as important as it is today．In the past only rich people could afford costly travel to other countries．But in 1976 one common person in twenty visited a country away from home． More people travel today than in the past mainly because there is a growing middle class(中产阶级) in many parts of the world．People now have more money to travel．Airplane fares at a bargain price (特价)for tourists make travel less expensive and thus more attractive than ever before． One person does not travel for the same reason as another．But more people enjoy seeing countries that are different from their own．They also travel to meet new people and try new foods． Tourism causes many changes in a country and in people's lives．People build new hotels and train native men and women as tourist guides．There are new night clubs and other amusements． International tourism is clearly a big business． 1．More people travel today than in the past mainly because ________． A．more people get interested in traveling B．traveling today is more popular than in the past C．people now have extra money for travel D．more people want to see other parts of the world with their own eyes 2．What makes travel more attractive than ever before? A．Special telegraph lines make travel less expensive． B．New hotels and restaurants are built now． C．More guides are being trained for tourists． D．Travel by plane to other countries is much cheaper today． 3．Which of the following is wrong? A．People travel for different reasons． B．Most people like to see foreign countries． C．When people travel they like to make good use of the plane． D．People like to learn from the people of other countries． 4．Which statement does this passage lead you to believe? A．Tourism will bring no changes in people's minds． B．Tourism causes only some changes in food and in clothing of a country． C．Tourism causes many changes in agriculture． D．Tourism causes obvious changes in many ways of a country．