Gas is a substance that can come in the form of a liquid (gasoline) or as something lighter than liquid, such as air.
In these sentences, gas is a liquid. We often use the word "gas" as a substitute for "gasoline."
My car ran out of gas.
Gas prices are climbing.
Give it some gas. (Push the car’s accelerator down with your foot.)
I gotta get some gas. (gotta = have got to)
This car is easy on gas. It gets good gas mileage.
In these sentences and questions, the word "gas" does not refer to a liquid. It’s much lighter than liquid. A gas might be colorless or odorless, depending on what kind of a gas it is.
Do you smell gas?
On our planet, methane is a type of gas, but on Titan, a moon of Saturn, methane is liquid.
Jupiter is a planet that is made up entirely of gas.
It’s a gaseous planet. ("Gaseous" is an adjective)
A gas leak forced the community to evacuate.
The Syrian government has been accused of using gas against its own people.
A gas attack killed and injured thousands of people in Iraq in the 1990s.
The dentist gave me some gas before going to work on a cavity. (gas = laughing gas or nitrous oxide)
Human beings are also capable of producing gas:
That burrito gave me gas.
No one knew it was David who was passing gas.
Someone’s got some really bad gas.
Broccoli leaves me feeling a little gassy. (The word "gassy" is an adjective.)
Sometimes the word "gas" is used in American slang to mean that an activity was a lot of fun.
