His book The Travel Notes of Xu Xiake, not only encouraged a love of travelling among Chinese people but provided important scientific information about the country's land and geography.
他的《徐霞客游记》不仅激发了中国人的旅游热情，还提供了有关中国土地和地理的重要科学信息。
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But when Rome collapsed in the fifth century and the Middle Ages began, direct trade of spices stopped, and so did that kind of hands-on knowledge of travel and geography.
AAA's predictions for holiday travel are based in part on an online survey of U.S. residents, whose answers are weighted based on factors including education, income and geography.