在英语学习中，掌握语法结构是非常重要的一步。其中，被动语态是一种常见的表达方式，它与主动语态相对应，用于强调动作的承受者而非执行者。为了帮助大家更好地理解和运用被动语态，下面是一些精心设计的练习题，供大家参考。

练习题一：改写句子

将以下句子改为被动语态：

1. They built this bridge in 1985.

- This bridge was built in 1985.

2. Someone cleaned the classroom yesterday.

- The classroom was cleaned yesterday.

3. The teacher corrected the students' homework.

- The students' homework was corrected by the teacher.

练习题二：填空题

根据上下文，在空白处填写适当的单词或短语，使句子成为被动语态。

4. The meeting ______ (hold) at 3 PM tomorrow.

- will be held

5. A new law ______ (pass) last year to protect wildlife.

- was passed

6. The book ______ (write) by a famous author last year.

- was written

练习题三：判断题

判断下列句子是否为被动语态，并说明理由。

7. "The cake was eaten by Mary."

- 是被动语态，因为强调的是蛋糕被吃掉的事实，而不是谁吃了蛋糕。

8. "Mary ate the cake."

- 不是被动语态，因为句子强调的是主语“Mary”完成了动作。

9. "The window is broken."

- 是被动语态，表示窗户的状态被改变。

通过以上练习题，我们可以更清楚地了解被动语态的使用场景和特点。被动语态通常用于描述客观事实、科学报告、新闻报道等场合，尤其是在需要突出结果或状态时更为常见。希望这些练习能够帮助大家加深对被动语态的理解，并在实际应用中更加得心应手。