例如：下面这句话为什么用with不用for:The reason why she had not stopped at the red light was most probably that her eyes had become weak (with)old age.分析：with是介词；而for表示“原因”时,通常用作连词...介词with和for的区别1：
with一般有“和”的意思，如with sb.，但接sth.的时候意思应该看语境；
for一般有“为”的意思，可以表示目的，如为某人、为了什么事，这时候可以用for。

介词with和for的区别2：
For(介词)：关于, 对于...来说, 考虑到...的事实
-- The weather is quite warm for November.
-- For him, this will be an entirely new hobby.
With(介词)：在某一方面 (多用于二者的比较)
-- With some people, pleasure is more important than work.
-- Some people may accept that excuse, but it won‘t work with me.


望采纳~~~
O(∩_∩)O谢谢