Answer:
1. boivent, de l'
2. buvez, du
3. de
Michel boit du jus d'orange
Explanation:
For the first one the verb has to be conjugated to fit "elles" because there is more than one person so the ending must be -ent. When talking about drinking or eating something use de la (for feminine), du (for masculine), and de l' (for words starting with vowel). So, here eau starts with e so we must use de l'.
For the second one, verbs after vous have to have an -ez ending. Café is masculine, so use du.
For the third one, if talking about drinking or eating in the negative drop the article and write just de.
For the last one, boit is the correct conjugation for a singular third person tense and orange juice is masculine so use du.