Which of the children used the wrong unit of measure?

Luna: I drank 7 gallons of orange juice after finishing my homework.

Alison: I poured 5 gallons of water into a beaker.

Anny: I bought 2 pints of milk from the supermarket.

Luna: 7 gallons of juice is too large. So unit is not suitable.

Alison: a beaker is too small to hold 5 gallons of water.

So the answer is Luna and Alison.