The sun is a source of ( natural / artificial ) light.
natural
Which lightbulb saves more energy?
LED
The glass is ( transparent / translucent / opaque ).
transparent
The sunglasses are ( transparent / translucent / opaque ).
translucent
The window is ( transparent / translucent / opaque ).
transparent
The box is ( transparent / translucent / opaque ).
opaque
The door is ( transparent / translucent / opaque ).
opaque
You should ( turn off / turn on ) the lights when you are not at home.
turn off
The car windows are ( transparent / translucent / opaque ).
translucent
A lamp is a source of ( natural / artifical ) light.
artificial