act or process bringing change. Exchanges of one set of clothes for another. To go from one train, bus, etc. and go to another.

Portable device that stores electricity.

To make something easier to understand.

Concerning light waves that are extremely short. ultraviolet part of spectrum.

happy and peaceful. Information in something, e.g. book or computer. satisfy.

Of or in the surrounding area or air.

on condition or understanding that. To make certain something will happen or be done.

materials used to wrap or protect goods. To put something into a container to store it.

sixty seconds. Records in writing what is said at a meeting.

thing that bears weight of something or keeps it upright. Things to hold up or prevent from falling down. To help prove or show that something is true.

In a way not requiring control by a person.

To carry out an action well or successfully.

To control or handle something, such as a machine.

either of pair of people engaged together in same activity. be partner of.

scientific procedure. To create and perform tests to research something.