use what if at the beginning of a question when we are asking
about the consequences of an action, particularly one that is undesirable.
We refer in this way to present or future circumstances:
if I am made redundant and have no work? What shall
we do then?
if there are jellyfish? You won't want to swim in the sea
can also use this structure to refer to past circumstances:
if the ice had cracked? You would have disappeared into the
icy water and wouldn't be here to tell us about it.
if you had slipped? You would've fallen right down
the cliff. There would have been nothing to save you.
you can see from these examples, what if questions give us
an alternative way of expressing conditional ideas. We could have
shall we do if I am made redundant and have no work?
won't want to swim in the sea, if there are jellyfish around.
the ice had cracked, you would've disappeared into the icy water
and wouldn't be here to tell us about it.
you had slipped, you would have fallen right down the cliff
none of these examples sound as dramatic as "what if...?".
Note that the final two examples in these sequences refer to imaginary
situations that did not occur, for which we need the so-called 'third'
supposing or what if?
can also use suppose or supposing as an alternative
to what if when we are asking about the consequences of
not going to take my umbrella.
~ Suppose it rains?
~ Supposing it rains?
~ What if it rains?
~ What will you do if it rains?
just caught the last flight of the day with two minutes to spare!
~ Suppose you had missed the flight?
~ Supposing you had missed the flight?
~ What if you had missed the flight?
~ What would you have done, if you had missed the flight?