问题详情

Men have travelled ever since they first appeared on the earth. In primitive times they did not travel for pleasure but to【C1】______ new places where their herds could feed, or to escape from hostile neighbors, or to find more【C2】______ climates. They travelled on foot. Their journeys were long, tiring, and often dangerous. They protected themselves with simple【C3】______ such as wooden sticks or stone clubs, and by lighting fires at night and, above all, by keeping together. Being intelligent and creative, they soon【C4】______ easier ways of travelling. They rode on the backs of their domesticated animals; they hollowed out tree【C5】______ and, by using bits of wood as paddles, were able to travel across water. Later they travelled, not from necessity, but【C6】______ the joy and excitement of seeing and experiencing new things, which is still the main【C7】______ why we travel today. Travelling, of course, has now become a highly organized business. There are cars and splendid roads, express trains, huge ships and jet airliners, all of【C8】______ provide us with comforts and security. This sounds wonderful. But there are difficulties. If you want to go【C9】______ , you need a passport and a visa, tickets, luggage, and a hundred and one other things. If you lose any of them, your journey may be【C10】______ .

【C1】

A．visit

B．find

C．purchase

D．explore

请帮忙给出正确答案和分析，谢谢！