Zero
If you heat ice, it (melt).
melts
If it rains tomorrow, I (take) an umbrella.
will take
If I won the lottery, I (travel) the world.
would travel
If I had known about the party, I (go).
would have gone
Water (boil) at 100 degrees Celsius.
boils
If she studies hard, she (pass) the exam.
will pass
If she were here, she (help) us.
would help
If she had studied, she (not/fail) the test.
wouldn't have failed
If you mix red and blue, you (get) purple.
get
If we leave early, we (not/miss) the bus.
won't miss
If we had a car, we (go) to the beach.
would go
If we had left earlier, we (arrive) on time.
would have arrived
If it rains, the ground (become) wet.
becomes
If he calls me, I (answer) right away.
will answer
If he were a doctor, he (help) people.
would help
If he had seen the movie, he (tell) us about it.
would have told
Plants (need) sunlight to grow.
need
If they finish their project, they (get) extra credit.
will get
If they knew the truth, they (be) upset.
would be
If they had listened to me, they (not/make) that mistake.
wouldn't have made