维生素C是一种重要的维生素，能防治坏血病，又称为抗坏血酸，其结构简式如图，下列有关它的叙述错误的是
A．它的分子式为C6H8O6
B．滴入淀粉和碘水的混合溶液，蓝色褪去，表现出还原性
C．它是一种水溶性维生素，高温易分解
D．在碱性溶液中能稳定地存在
答案：D
题目分析：维生素C 酸性，具有较强的还原性，加热或在溶液中易氧化分解，在碱性条件下更易被氧化，所以D错误。
| 阅读理解。 | |
| Venice (威尼斯) is in the northeast of Italy. It wasn't built on land, like Beijing or Shanghai, but on more than 110 islands. Seawater is everywhere around the city. Even so, travel isn't that difficult. The waterways have always been the best way to get around. There are 117 waterways and more than 400 bridges that can lead you where you want to go. People in Venice move from place to place by boat. They like to enjoy cool summer nights while taking boat trips. They can talk to other people as they go along. Venice grew out of small islands in saltwater lakes when some Italians escaped (逃跑) from a war more than 1,500 years ago, and built homes there. | |
选择恰当的短语填空：
city, it is not difficult for people to 4. . Because there are many 5. and 6. , and people can move by 7. . They enjoy taking boat trips on 8. and talking to others as they 9. . The history of Venice is very long. More than 1,500 years ago, some Italians 10. from a great war and they built homes there. |