It is used when there is no light
Light bulb
It is used to send letters
stamps
It is used when it rains
Umbrella
It is used to clean dirty dishes
Dishwasher
It is used when your are wounded
plasters
It is used to order papers
paper clips
It is used to warm food
microwave
It is used to investigate
Microscope
It is used to learn the meaning of a word
Bilingual dictionary
It is used when you have a fever
Digital thermometer
