1 . 21世纪目睹了人类社会的飞速发展。
____________the high-speed development of human society.

2 . 此外，还播放了关于三年生活的视频，这些视频见证了我们成长的整个过程。
What’s more, videos about the three years’ life, which ________________, were played.

3 . Many great historic events happened in the city. (改为地点名词作主语)
____________________________________________________________________________

4 . The past 50 years _________________________________of our school.
过去的50年见证了我们学校的兴衰。

5 . 我亲眼见证了这对年轻的夫妻如何熬过了他们人生中最困难的时期。
I ________ how this young couple ________ ________ the most difficult time in their life.

6 . When he walked out of the park, the old man happened to see the road accident.
→　________, the old man happened to ________ the road accident.(分词作状语)

7 . 穿得破破烂烂的男孩在附近走家串户卖爆米花。
The neighborhood ________________popcorn from door to door.

8 . 这几年我们见证了中国在许多方面的巨大变化。
All these years we ________in China in many aspects.

9 . The_________who_________the incident_________ the police and promised to be a_________.
这个目击了这起事故的目击者向警察提交了证据并且答应做证人。

10 . 司机作证说，他看到此人进入那栋大楼。
The driver_________________ the man enter the building.