Read the following sentence and find out which type of conjunction the underlined ones are.
You will not get the promotion ______ you work hard for it.

The correct answer is: Unless

We use the conjunction 'unless' to mean 'except if'. We use 'unless' to say that there may be an exception and that this exception will change the situation. When 'unless' comes before the main clause, we use a comma. 'You will not get the promotion, unless you hard for it', which means, if he needs promotion, he should work hard for it.