Ⅲ. Key structures. 关键句型。
A) Underline the passive voice in 3a. 画出 3a 中表示被动语态的动词。
B) Give the correct form of the verbs in parentheses. Do not refer to the passage until you finish your exercise. 用括号中动词的正确形式填空，完成练习后再对照课文，核对你的答案。
1. Did you know that tea (invent) by accident?
2. Many people believe that tea first (drink) about 5000 years ago.
3. It (say) that a Chinese ruler called Shen Nong was the first to discover tea as a drink.
4. The book describes how tea plants (grow) and (use) to make tea.
5. It also discusses where the finest tea leaves (produce) and what kinds of water (use).
6. It (believe) that tea (bring) to Korea and Japan during the 6th and 7th centuries.

Ⅲ. 1. was invented 2. was, drunk 3. is said 4. were grown, used 5. were produced, were used 6. is believed, was brought