"Do you see sixteen elephants?"
Translation:Zien jullie zestien olifanten?
Because 'zien' is the 1st, 2nd and 3rd person plural form of the verb. 'Jij' is second person singular, which means it ends on a -t. However, when the verb comes before the subject (like in a question), the -t is dropped (this only works for 'jij/je'). So the sentence: 'Zie jij zestien olifanten?' is correct.