'So' when used with an adjective, shows extreme situations. This form is used mostly in speech:
The music is so loud! Why don’t they turn it down?
The hotel was so good. It was worth every cent.
The combination can be used with 'that' to show results. However 'that' can be omitted:
The music is so loud that I can't sleep well.
The hotel was so good that we’re staying there next year.
The music is so loud I can't sleep well.
The hotel was so good we're staying there next year.
'So' when used with an adverb describes extreme actions. His form is mostly used in speech:
He spoke so well! He sounded like a politician.
He plays so well! He will soon become professional.
This combination can be combined with that to show results. However 'that' can be omitted:
He spoke so well (that) he had everyone on his side.
He plays so well (that) he got a standing ovation.
When 'so' is used with 'many' or 'few' and a plural noun it is showing extreme quantities.
I was surprised that she knew so many people.
There were so few people at the demonstration that I felt very discouraged.
Even here 'that' can be omitted.
When 'so' is used with 'much' or 'little' and a non-count noun it is showing extremes in amount.
Peter has so much time on his hands yet he just lounges around at home.
Sarah is always rushed off her feet. She has so little time to meet us.
When 'so' is used with 'often' or 'rarely' it is used to describe how often something happens:
I see Peter so often that people are starting to think we are an item.
I meet my sister so rarely! I miss her so much.
'Such' with an adjective and a noun shows extremes. This form is mostly used in speech:
It was such a good hotel (that) we are staying there next year.
He is such a good pianist (that) I’m sure he will become a professional soon.
'That' can be omitted.
So or such can be used to express the same idea but remember that 'so' is not used with a noun. 'Such' can be used with a noun.
Her eyes are so beautiful (that) it is difficult to concentrate when she speaks to you.
She has such beautiful eyes (that) it is difficult to concentrate when she speaks to you.
'Such' can also mean 'this/that type of...'
I've never seen such enthusiasm from government workers before.
Peter has never made such mistakes.
The actor doesn't usually receive such acclaim for his work.
Lesson by Tristan, teacher at EC Malta English school
Now complete the following with either 'so' or 'such'.