"Our cat drinks milk."
Translation:Onze kat drinkt melk.
Elardus is right, when it's de kat is onze kat. But when is for example anything with het like het ei, it's ons ei.
FUN FACT: In Flemish (and several Dutch dialects), people use ons for people or beings they consider as close as family members. So in this case "Ons kat drinkt melk" could work, but indicates you consider the cat as a part of your family and are speaking on behalf of the family.
Because that's how the conjugation of drinken in the simple present goes for the third person singular.
The 1st person singular uses only the stem of the verb.
The second and third (singular) use the stem of the verb+t
All the plural ones use the same verb form as the infinitive.
Hope this helps.