What is the right word to the gap (21)? (had/have)

That is about 400 years earlier than when the Inca Indians were thought to (21) __ discovered the silver in the ground.

I think it's had as the tense before is past simple, but the official solution is have Which one is the right anwser?

closed as general reference by tchrist, MetaEd, Kristina Lopez, Mitch, user21497 May 9 '13 at 1:14

This question is too basic; it can be definitively and permanently answered by a single link to a standard internet reference source designed specifically to find that type of information. If this question can be reworded to fit the rules in the help center, please edit the question.


To have. One should definitely use the infinitive. "He seemed to walk straight", "she was told to listen carefully".

  • Thanks for posting an answer. Please support it with references (such as a link to a reputable source). Also check spelling. Thanks. – MetaEd May 8 '13 at 15:38

Have is right. After to you cannot have a past tense word - here 'had'. To +verb is infinitive . All infinitives will have 'to' and the base verb. (which is always present tense. it is also called as root verb.