In mathematics, as soon as the number is similar to the lowercase L of English letters, it is easy to confuse how many liters to write.

In addition, in physics, the letter L usually represents the equivalence of displacement and distance, and the use of L in units will also cause unnecessary conflicts. However, ml mL is unlikely to cause trouble in these aspects, and lowercase is also an international standard, and it needs to be raised with a capital L.

Because milliliter is not an international unit, the international unit stipulates that it should be raised to L, and one thousandth of a liter is naturally milliliter. What I said above is uppercase, not lowercase. To answer your question, you have to say that there is an L in the international unit before there is a mL.

Personal opinion, for reference only.