只有当引导词that做定语从句的宾语成分时可以省略,其他情况不能省略。
The man [(that) I saw in the street yesterday] is my teacher.
The man [that said hello to me yesterday] is my teacher.
The village [(that) I often visit] is my hometown.
The village [that becomes a modern city] is my hometown.
注:带()的that可以省略,[ ]括着的是定语从句。