5. The man began to work when he was 20 years old.(改为同义句) 

The man began to work  20.

4. She could speak English.(对画线部分提问) 

 could she speak?

3. She became famous two years ago.(对画线部分提问)

she famous?

2. He started to learn to swim.(改为一般疑问句)

he to learn to swim?

根据要求完成句子

1. The man joined the army.(改为否定句) 

The man    the army.

7. 他打算去环游世界。

He plans to travel   .

6. 昨天他幵始学习弹钢琴。

He   to play the piano yester?day.

5. 请用英语回答我的问题。

Please answer my question .

4. 山上有数百棵树。

There are  on the hill.

3. 操场上有三百名学生₌

There are students on the playground.