from Italy asks:
What happens when the contract will be expired?
Also, can I use happen like this?
5. I don't happen to be a teacher.
In your first four listed examples above, Ruben, you are referring to future time, but only 2 and 3 are grammatically correct.
Let's look at the arrangement of structures in your second sentence.
behaves like if in subordinate clauses of this kind and remains
in the present tense when we are referring to a future condition.
Consider the following:
look now at the arrangement of structures from your third sentence.
If we are discussing a general truth, rather than a specific instance
or event, the main clause usually remains in the present tense as
well as the tense in the if or when clause. Consider
For your fourth sentence, remember:
no does/do/did when what/who question refers to the subject.
'wh-' questions, like what, who or which, refer
to the subject of the sentence, we do not use the auxiliary forms
do/does/did. These auxiliaries are used only when the wh-question
refers to the object. Compare the following:
fifth sentence happen can be used with a following infinitive
to suggest that something may happen by chance. Consider the following: