Questions & Answers about Þeir drekka mjólk.
This drekka is the present-tense, third-person plural form of drekka (to drink). In Icelandic the plural endings in the present tense are:
• við drekka (we drink)
• þið drekkið (you pl. drink)
• þeir/þær/þau drekka (they drink)
So both við and þeir share the ending -a.
Here mjólk is in the accusative singular (direct object) but for this feminine noun the nominative, accusative, and dative are all mjólk. Its full singular declension is:• Nominative mjólk• Accusative mjólk• Dative mjólk• Genitive mjólkar