Subjunctive with expressions of doubt

Question 1

1. When expressing doubt or uncertainty about an action or a condition, you must use the subjunctive. The following are some common expressions of doubt that require the use of the subjunctive:

Dudar (to doubt) que No estar seguro(a) que
No creer que No ser cierto/verdad/obvio/evidente que
No pensar que No suponer (to suppose) que

Answer 1

Dudo que la cebra corra más rápido que el león.
I doubt that the zebra runs faster than the lion.

No pensamos que los elefantes duerman.
We don’t think that the elephants are sleeping.

Question 2

2. When using the expressions below to affirm a belief or express certainty, you must use the indicative.

Creer que Estar seguro(a) que
Pensar que Ser cierto/verdad/obvio/evidente que
Suponer que

Answer 2

Supongo que a veces la caza es necesaria.
I suppose that sometimes hunting is necessary.

Es obvio que necesitamos hacer algo.
It is obvious that we need to do something.

Question 3

3. When using the verbs pensar and creer in a question, it is common to use the subjunctive in the dependent clause as you are not affirming a belief.

Answer 3

¿Crees que haya suficiente comida para los animales?

Do you think there is enough food for the animals?

Question 4

Investiguemos la gramática

Answer 4

While the expression dudar always requires the subjunctive, there is variation in its use with no dudar. Some speakers will use the subjunctive (doubt) or the indicative (certainty), depending on their intention. You might prefer to use an expression of certainty like estoy seguro(a) or es cierto if you mean that you are completely sure about something.