let alone 也看作一种连词

let alone的用法：后面要接名词，动词进行时，或与前半句时态相同。

1.There isn't room for all of us, let alone six dogs and a cat.这儿连我们的地方都不够，更不用说六只狗和一只猫了。

2.I don't even know him, let alone falling in love with him! 我根本就不认识他，更不用说爱上他了！

3.I haven't decided what for dinner yet, let alone brought the food.我都还没决定晚饭做什么菜呢，更别提买好了。

“Their ancestors had been dirt poor and never saw royalty, let alone hung around with them”(Garrison Keillor)

He would never walk again let alone play golf.

We were trapped in a situation you can barely imagine, let alone understand.