clausal substitution

lexical verb ellipsis only

lexical and auxiliary verb ellipsis

noun phrase ellipsis

subject and lexical verb ellipsis

lexical verb substitution

Do you want the strawberry or the chocolate ice-cream cone?
The chocolate.

He usually takes a walk in the evening but probably won't in this rain.

My doctor told me to diet so I will.

I hated the book and so did she.

The party might get a bit noisy.
If so, I'll leave early.

Could you have been imagining it?
I could, I guess.