if

Take one if you are hungry.

Take one if you are hungry.

If you don't know the answer, just take a wild guess.

If you don't know the answer, just take a wild guess.

Scientists will test the new medicine to see if it works.

Scientists will test the new medicine to see if it works.

If you don't have coffee, you can have tea instead.

If you don't have coffee, you can have tea instead.

You should seek medical advice if the symptoms become serious.

You should seek medical advice if the symptoms become serious.

Please contact me if you have any questions.

Please contact me if you have any questions.

Please raise your hand if you have any questions about the assignment.

Please raise your hand if you have any questions about the assignment.

He was afraid he might fail the exam if he didn't study harder.

He was afraid he might fail the exam if he didn't study harder.

I felt a cold breeze and wondered if there was a ghost in the house.

I felt a cold breeze and wondered if there was a ghost in the house.