1st conditional
If you dance with a boy, all the girls ... (be) jealous of you.
If you dance with a boy, all the girls will be jealous of you.
When do we need the 1st conditional?
When we want to explain situations with a high possibility of happening
I'm going to town tomorrow. __________ you need anything, call me.
I'm going to town tomorrow. If you need anything, call me.
When do we use the 2nd conditional?
For hypothetical situations