Final answer:
The word 'preguntar' cannot complete the sentence because it does not fit grammatically.
Step-by-step explanation:
The word 'preguntar' cannot complete the sentence 'Necesito ______ a mi amigo.' because 'preguntar' means 'to ask' and it does not fit grammatically into the sentence. The correct word to complete the sentence would be 'ayudar' which means 'to help' or 'comprar' which means 'to buy'.
Learn more about Completing a Spanish sentence