If the telephone rings,
If I have a headache,
I won't sleep
If the computer doesn't work,
If it isn't sunny tomorrow,
If it doesn't rain,
If he doesn't read the map,
If you send the letter today,
we will go to the beach.
he will get lost.
it will arrive tomorrow.
the picnic will be cancelled.
I will call a technician.
do not answer it.
I will take an aspirin.
if I drink coffee.