剛和Virgin Atlantic通了話，特將他們的回複與各位分享。。。

Ready to drink milk in carton is ok to be take on the flight.However, when pass the security check, the officer might ask the adult to sample the milk. 嘿嘿， 就是試喝，以證明不是什麽化學液體。。。I hope it helps.
I will fly to LA in early November.