1. Thousands of people gathered in the city square to protest against the government's new policy.
成千上万的人聚集在市广场上，抗议政府的新政策。

2. The company has invested thousands of dollars in research and development.
该公司已经投入了数千美元进行研发。

3. It took me thousands of hours of practice to become proficient in playing the piano.
我花费了数千个小时的练习才能熟练地弹钢琴。