you inhale oxygen and exhale carbon dioxide.
The air in a basketball lets the basketball bounce.
You exhale air.
It lets air in for various purposes.
air
Lungs
Your lungs lets out air and it travels through your nose
eggs
engine lets airoplane fly in air and airoplane also fly with its wings
A filter is a device to strain out substances you don't want from the stuff you do. A coffee filter strains out the grounds and lets the coffee pass through. An air filter strains out impurities in the air and lets the purer air through. A spam filter strains out the e-mails you don't want and lets the ones you do want through.
eave
lets warm air in when it reaches a certain temperature.
Yes, but it also lets out the hot air from the attic.