the reason for 和 the reason why 怎么用

正确说法在这儿。

英语里 the reason for 和 the reason why 都能用，意思一样，但搭配不太一样。

the reason for 后面接名词。比如：
🔸the reason for the delay
🔸the reason for his anger
🔸the reason for the change

the reason why 后面接从句。比如：
🔸the reason why he left
🔸the reason why prices increased
🔸the reason why she was upset

有人觉得 why 是多余的，因为 reason 和 why 作用差不多。所以也可以说 the reason he left was...，或 the reason prices increased was...。

for 后面也可以接动名词：
✅I don't know the reason for her ignoring my message.

这样写有点怪，但 ignoring 变成了动名词（也就是名词），就可以跟 for 了。