1. The Subjunctive to Express Doubt and Denial
(El subjuntivo usado para expresar duda y negación)
Dudo que las grasas transformadas sean buenas para la salud.

2. The Subjunctive to Express Doubt and Denial
The subjunctive is used in noun clauses after expressions of doubt, uncertainty, or denial. The following verbs can express doubt and denial. Unlike the verbs that express volition and emotion, these verbs do not require a change of subject in the dependent clause in order to use the subjunctive.
dudar
to doubt
negar (ie)
to deny
no pensar (ie)
to not to think
no creer
to not believe
no estar seguro/a (de)
to permit

3. The Subjunctive to Express Doubt and Denial
The subjunctive is used in noun clauses after expressions of doubt, uncertainty, or denial. The following verbs can express doubt and denial. Unlike the verbs that express volition and emotion, these verbs do not require a change of subject in the dependent clause in order to use the subjunctive.
Dudo que Camilo padezca de artritis.
I doubt that Camilo suffers from arthritis.
No creo que el médico sepa el diagnóstico.
I don’t believe that the doctor knows the diagnosis.

4. The Subjunctive to Express Doubt and Denial
The subjunctive is used in noun clauses after expressions of doubt, uncertainty, or denial. The following verbs can express doubt and denial. Unlike the verbs that express volition and emotion, these verbs do not require a change of subject in the dependent clause in order to use the subjunctive.
No estamos seguros de que las grasas transformadas sean nocivas.
We’re not sure that transfatty acids are harmful.
Mi padre niega que tenga un nivel muy alto de colesterol.
My father denies that he has a very high cholesterol level.

5. The Subjunctive to Express Doubt and Denial
When there is no doubt, uncertainty, or disbelief about an action or event, and when the subject appears certain of the facts, the indicative is used in the noun clause. For most expressions of doubt or uncertainty, the indicative will be used for the opposing expression (dudar versus no dudar; no creer versus creer).
No dudo que Camilo padece de artritis.
I don’t doubt that Camilo suffers from arthritis.
Creo que el médico sabe el diagnóstico.
I believe that the doctor knows the diagnosis.

6. The Subjunctive to Express Doubt and Denial
When there is no doubt, uncertainty, or disbelief about an action or event, and when the subject appears certain of the facts, the indicative is used in the noun clause. For most expressions of doubt or uncertainty, the indicative will be used for the opposing expression (dudar versus no dudar; no creer versus creer).
Estamos seguros de que las grasas transformadas son nocivas.
We’re sure that transfatty acids are harmful.
Mi padre no niega que tiene un nivel muy alto de colesterol.
My father does not deny that he has a very high cholesterol level.

7. The Subjunctive to Express Doubt and Denial
When the verb creer is used in a question, it can imply doubt in the mind of the speaker, thereby triggering the subjunctive in the dependent clause.
¿Crees que el alcohol dañe el corazón?
Do you believe (think) that alcohol damages the heart? (speaker implies doubt)
If the speaker expresses no opinion or does not anticipate a negative response, the indicative is preferred.
¿Crees que el alcohol daña el corazón?
Do you believe (think) that alcohol damages the heart? (speaker has no opinion)

8. The Subjunctive to Express Doubt and Denial
The subjunctive with tal vez and quizá(s)
The expressions tal vez and quizá(s), meaning perhaps or maybe, are followed by the subjunctive when the speaker wishes to convey uncertainty or doubt. Both expressions are used without que.
Tal vez funcione no comer tanta grasa.
Perhaps not eating so much fat will work.
Quizás el ejercicio me alivie la artritis.
Perhaps exercise will alleviate my arthritis.

9. The Subjunctive to Express Doubt and Denial
The subjunctive with tal vez and quizá(s)
When tal vez or quizá(s) follows the verb, the indicative is used.
Vamos a fumar menos, tal vez.
We’re going to smoke less, perhaps.
Bajo de peso, quizás.
I’ll lose weight, maybe.

10. FIN