但相对于runoutof来说却可以省略,

Question

但相对于run out of来说却可以省略,

Answer 1

run out 和run out of不一样,run out 有“被用完”的意思,
如：The gas in the car ran out.
但是,run out of sth.是“用完.” 如果sth.做主语,用被动语态,of 一样不能省略,如：
I ran out of the gas.
The gas was run out of.