Final answer:
The word that cannot complete the sentence is 'comprar'
Step-by-step explanation:
The word that cannot complete the sentence is comprar.
'Necesito' is a Spanish verb that means 'I need' or 'I require'. To complete the sentence, you would usually follow 'necesito' with a direct object. In this case, the direct object is 'mi amigo', which means 'my friend'.
The other options provided—'ayudar', 'preguntar', and 'visitar'—are also Spanish verbs that mean 'to help', 'to ask', and 'to visit', respectively. All three verbs can be used to complete the sentence, whereas 'comprar', which means 'to buy', does not fit in the given context.
Learn more about Completing Spanish sentences