It means saving or protecting something:

It means to change from one thing into another:

When something is happening now we say it is:

It is a form of energy that can produce light, heat, and power.

It means to move freely.

It means to make something from other materials.

It is the ability or strentgh to do something.

When you can use something many times, and it is not over.

It is something that people need and use.

When there is not a lot of it, we say it is:

Wind is a ..... resource.

Water can be very .... in the desert.

The .... of the earthquake destroyed the building.

People use .... to power their appliances.