Iron - to make clothes flat and smooth using an iron. I need to iron a shirt to wear tomorrow.
Unless - except if. I won't call you unless there are any problems.
Find out - to get information about something, or to learn a fact for the first time. Peter was shocked when he found out what we had done.
Narrow - a small distance from one side to the other. A narrow lane/street
Narrow down - to make something, for example a list or a choice, smaller and clearer by removing the things that are less important. We've managed to narrow the list down to four.
Extensive - large in amount or size. An extensive art collection