____在不断改变地表的地形地貌，也会使土地流失，影响我们的生活。

设a＜0，在代数式|a|，-a，a²⁰⁰⁹，a²⁰¹⁰，|-a|，（$\frac{a^2}{a}$+a），（$\frac{a^2}{a}$-a）中负数的个数是（　　）

A

    An Englishman was showing a foreign visitor around London.“What's that strange building?” asked the visitor.“That's the Tower (塔) of London.”“I see. How long did it take to build it?”“About 500 years.”“In my country we can build it in a few months.”said the visitor. After they came to St. Paul's Cathedral (大教堂), the visitor asked the same question. “Nearly forty years,”said the Englishman. “In my country we finish it in forty days at most,” said the visitor. This went on all day. They visited most of the best known buildings in the city. Every time they saw a new one, the visitor asked what it was and how long it took to build it. Then he said they could do the same thing much faster in his country. At last the Englishman got angry with the visitor though he tried not to show it. Several days later they came to the House of Parliament (议会) and the visitor asked his usual question, “What's that?” The Englishman answered, “I have no idea. It wasn't there last night.”

根据短文内容，选择正确答案。