"If you are not smart, you could not solve the problem".<br/><br/>I know "could" can be used for the past of "can" and for subjunctive mood, but I think the sentence above should be <br/><br/>"If you were not smart, you could not solve the problem", or<br/><br/>"If you are not smart, you can not solve the problem", Otherwise, present tense in if- clause can be written with could, would,etc?<br/><br/>What do you think? Please help me and thank you as usual in advance,