For example, a flashlight contains a circuit whenever it's turned on--the current flows from the battery's positive terminal, through the switch (which is on), through the filament of the light bulb (which glows), and back to the battery's negative 
(a flashlight; contains; a circuit whenever it's turned on) (it; 's turned on; L:a circuit) (the switch; is; ) (the light bulb; glows; )
a flashlight it the switch the light bulb
contains 's turned on is glows
a circuit whenever it's turned on
L:a circuit