20世纪见证了全球范围内巨大的社会和政治变革。

The 20th century ___saw tremendous social and political changes across the globe.

该国去年见证了可再生能源投资的显著增长。

The country ___saw a significant rise in renewable energy investment last year.

我们的城市每年夏天都会迎来成千上万的游客。

Our city ___sees thousands of tourists every summer.