A、The shape of different kinds of tea. B、The temperature of making tea. C、The different places of tea. D、The roasting and fermen

Wherever Chinese go, the custom of drinking tea follows. Tea was first discovered by Chinese. Tea is an indispensable part of the life of a Chinese. A Chinese saying identifies the seven basic daily necessities: Firework, rice, oil, salt, soy sauce, vinegar and tea. The custom of drinking tea as fuel and rice has been ingrained in Chinese for over a thousand years. (16)In Tang Dynasty，a man named Lu Yu created the first compendium in the world on tea, Book of Tea. This work helped to popularize the art of tea drinking all across China.
Tea is made from the young, tender leaves of the tea tree. (17)The differences among the many kinds of tea available are based mainly on the roasting and fermentation of the tea leaves. Through fermentation, the originally deep green leaves become reddish-brown in color. The longer the fermentation, the darker the color. Depending on the length of the roasting and degree of fermentation, the fragrance can range from floral to fruity and so on.
Tea is China’s national drink. It contains vitamins, chlorophyll，essential oils, and fluoride. It is diuretic and capable of improving the eyesight as well as increasing alertness, so (18)Chinese believe that frequent tea drinkers enjoy a longer life span. Its medical properties and benefits to the human body have actually been scientifical1y proven, and tea has come to be generally recognized as a natural health food.
Questions 16 to 18 are based on the passage you have just heard.
16.In which dynasty was Book of Tea created?
17.What’s the basis of differences among the many kinds of tea?
18.What do Chinese think of drinking tea?