not to mention, let alone
这两者都可用如连词,它们的区别仅在于:not to mention后只接名词短语,而let alone后可接任何词。另外, let alone只用于非正式语体中,且多用于否定句。例如:
I had never seen him, let alone spoken to him.我从未见过他,更不用说与他交谈了。
not to mention, not to say
这两个短语都可表示对某一事物的说明,但有区别。试比较:
I don't know English, not to mention French.
我连英语都不懂,更别说法语了。
(两件事,追补)
It is warm today, not to say hot.
今天虽说不上多么热,可也够暖和了。
(一类事,不同程度)