"Er sieht ein größeres Pferd als sie."

[yaliyev]

I think the following translation is also correct: He sees a horse bigger than it.

[christian]

I don't think so.

[jpentland]

If the "it" was referring to an inanimate feminine object surely that would be correct?

[christian]

What inanimate feminine object do you have in mind? I can't think of any that would make sense here.

[jpentland]

Eine Kamera maybe?

[christian]

That doesn't really work.

[wataya]

"Die Stute" might work grammatically as a possible referent for 'sie'. But that's not good German. Duo's interpretation is by far the most natural one.

[wataya]

That's perfectly fine but notice that the sentence is ambiguous. The 'sie' could refer either to one of the mares or to a woman who sees the bigger mare. This latter interpretation is the more natural one (that is: without further context, of course). You can avoid the ambiguity by using a different pronoun, e.g. 'Er sieht eine größere Stute als diese'.

[BB__]

Let's say you're referring to two mares. Could you say "Er sieht eine größere Stute als sie" and if not, what would be the correct sentence?

[jpentland]

Why can't "sie" mean you in this case?

[christian]

It can mean "she" or "they", but it can't mean "you" because it's not capitalised.