The difference between 'present real' conditionals and 'future real' conditionals can be confusing,

and sometimes, both types can be correct for the same sentence.

Look at each 'real if' example below, and think about the time involved - is it a fact? → use 'present real'. 

Is it a frequency situation, like 'always' or 'never' or 'sometimes'? → use 'present real'.  Or, does it talk

about something that may happen in the future? → use 'future real'.

In some cases, both answers are correct - because it's both a fact and a thing that can happen

in the future. So, for sentences like that, be sure to choose answer "C".

For example, both of the following sentences are correct:

• If you heat water to 212° F, it boils.

• If you heat water to 212° F, it will boil.