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Can I say,

He carried a tank of gas.
Comments  
of course you can.
So, there are all same in meaning and correct?

(a) He carried a tank of gas / a gas tank / a gas of tank.
Students: Are you brave enough to let our tutors analyse your pronunciation?
a gas of tank is incorrect

a tank of gas is most polite

a gas tank can sometimes sound scarey to the wrong people.