not to speak of 与not to metion有什么区别

not to speak of是“更不用说”的意思，与to say nothing of和not to mention同义，并可通用。

例：PLA men defy death， not to speak of hardship．解放军战士死且不怕，更不用说艰苦了。

其中not to speak of 可以同not to mention 替换