"A tiny dog."
Translation:Cù beag bìodach.
A tiny dog is not actually a sentence, it is a phrase. If you are asked to do a sentence there will be a subject and a verb plus something else like an adjective. If you wanted to say 'A dog is tiny' that is a sentence using the verb 'is'. In Gaelic is would be translated with tha, so you would need to write 'Tha cù beag biodach.' Hope this makes sense!