• To make a sentence negative, we use DID NOT before the main verb, and we use the verb in the INFINITIVE:
  
  Columbus discovered America.
  He did not discover Australia.
  
  
• To make a sentence interrogative, we use DID before the subject, and we use the verb in the INFINITIVE:
  
  Captain Cook discovered many islands in the Pacific Ocean.
  Did Captain Cook discover Hawaii?
  

JJCC