就是跟中文中的扩句一样，用that，which，who或whose引导的定语从句完成句子

The survivors that had been missing for a whole week were dug out by soldiers.
The survivors which we heard about were dug out by soldiers.
The survivors who went missing a week ago were dug out by soldiers.
The survivors whose names were unknown were dug out by soldiers.

The nation that was once so strong was shocked at the news.
The nation which was once so naive was shocked at the news.
The nation whose people were so ignorant before was shocked at the news.