2. When are windows the weak link in a building？
A In the cold winter.
B In the hot summer.
C When air conditioners are turned on.
D Both A and B.
3. What are smart windows，according to Paragraph 4？
A Windows that are coated.
B Windows that are glazed.
C Windows the color of which can be changed.
D Windows that have many layers.
4. To make electrochromic windows change color，what is applied to the window glass？
A Electricity.
B Tungsten oxide.
C A battery.
D A voltage.
5. What will he the benefit if the research on smart windows turns out to be successful，according to the last paragraph？
A The buildings will look different.
B Windows can be as large as you want.
C We may not need air conditioners any more.
D They are less expensive than traditional windows.
答案与题解：
1. A 第一段告诉我们窗户因为让阳光进入房间，并且为房间提供热源，所以节约了能源。第二段说，窗户使人们能接触外部世界。所以B、C和D都说明了窗户的重要性。第一段最后一句说，研究者正在实验能让窗户变换亮度，但并没有说已经实验成功，所以A是错误的说法，是正确选择。
2. D 短文第三段的第一句说：windows are the weak link in a building，接下来是对这句话分寒冬和炎夏做了说明。所以D是正确选择。
3. C 第四段告诉我们，多年来，科学家已研究出多种通过窗户节能的办法，而smart windows 使用的技术使窗户能变换颜色。所以C是正确选择。
4. B 第五段第二句提供了答案。a sheet of glass coated with thin layers of chemical compound such as tungsten oxide中的coated是“涂上一层薄薄的……”的意思。
5. C 短文最后一段的第五句提供了答案。