d) I was so tired that I couldn't sleep
e) I was tired so that I couldn't sleep
Of these two examples d) is perfect and e) simply doesn't work.
d) is the correct form of e) or an alternative would be I was too tired to sleep.
One of my friends has explained this to me. Nevertheless, I couldn't get why E is incorrect.
there — at the link– has been written tow kinds of "so that", hasn't been written? if so, we could use them interchageably by the meaning both result and purpose.
I have underlined what I mean:
Best Answer
The phrase "so that" means "for the purpose of". It shows intent or purpose.
The sentence "I was tired so that I couldn't sleep" doesn't make sense.
This is difficult to read sensibly. It might mean that you made yourself tired with the intention of not being able to sleep.
On the other hand, so... that... is different from so that. It indicates that an extreme condition causes some consequence: