It is strange that he (should) have left withoutsaying doodbye .

问题描述:

It is strange that he (should) have left withoutsaying doodbye .
在这句话中should怎么翻译啊?为什么可以省?说一下should的用法

It is strange that he (should) have left withoutsaying doodbye .
should:竟然
句意:他竟然一句话没说就离开了
多谢!