Final answer:
The best Spanish word to complete the sentence is 'vender.' It means 'to sell' in English.
Step-by-step explanation:
The best Spanish word to complete the sentence 'Tenemos que vender muchos carros.' is vender, which means 'to sell' in English. This choice is appropriate because the context suggests that the subject must sell many cars. For example, if the sentence is 'Tenemos que vender muchos carros para ganar dinero,' it means 'We have to sell many cars to earn money.'
Learn more about Completing sentences in Spanish