Breakdown of Si tu dis un mensonge, tu croiseras les doigts.
tu
you (informal singular)
si
if
dire
to say, to tell
le mensonge
the lie
Questions & Answers about Si tu dis un mensonge, tu croiseras les doigts.
Why is dis in the present tense if the sentence is about the future?
This is the first conditional structure. In French (just like in English), when you use si (if) to talk about a likely future condition, the verb directly after si is in the present tense (tu dis). The result part of the sentence uses the future tense (tu croiseras).
How do we form the future tense croiseras here?
Croiser (to cross) is a regular '-er' verb. To form the futur simple, you take the whole infinitive word (croiser) and add the future ending for tu, which is -as. This gives you tu croiseras (you will cross).
What is the infinitive verb for dis?
It is the irregular verb dire (to say or to tell). Even though we are talking about a future lie, we use the present tense tu dis because it is part of the si clause.
Why does it say les doigts (the fingers) instead of tes doigts (your fingers)?