Number + 加仑 + (的 + Noun)
加仑 (jiālún) is a transliterated loanword classifier used to count quantities in gallons, a unit of liquid measurement. It is used when discussing volumes of liquid, especially in news or scientific contexts involving Western measurement systems. A number is placed before 加仑 to indicate the quantity.
这辆车加了十加仑的汽油。
Zhè liàng chē jiāle shí jiālún de qìyóu.
This car was filled with ten gallons of gasoline.
美国人通常用加仑来计量牛奶的容量。
Měiguó rén tōngcháng yòng jiālún lái jìliàng niúnǎi de róngliàng.
Americans usually measure milk by the gallon.
那个水箱能装五十加仑的水。
Nàge shuǐxiāng néng zhuāng wǔshí jiālún de shuǐ.
That water tank can hold fifty gallons of water.