Spanish Doubt vs Uncertainty

What tense do you use for doubt?

subjunctive

What tense do you use for certain?

present

Is dudar doubt or certainty?

doubt

Is es dudoso doubt or certainty?

doubt

Is no estar seguro doubt or certainty?

doubt

Is no creer doubt or certainty?

doubt

Is no es cierto doubt or certainty?

doubt

Is no es verdad doubt or certainty?

doubt

Is quizás doubt or certainty?

either

Is tal vez doubt or certainty?

either

Is no dudar doubt or certainty?

certainty

Is creer doubt or certainty?

certainty

Is es cierto doubt or certainty?

certainty

Is es verdad doubt or certainty?

certainty

Is es seguro doubt or certainty?

certainty

Is no es dudoso doubt or certainty?

certainty