请根据课文内容回答以下问题 1. What was special about the World Trade Center in New York? 2. What makes Americans feel uneasy about extremely tall buildings? 3. What do some experts think of skyscrapers now? What is your idea about skyscrapers? 4. How many ways of restoring the World Trade Centre are mentioned in the passage? 5. What technical development made skyscrapers possible?