word choice - so+adj+that structure

My question is when you do the so+adj+that structure, do you have to remove the pronoun ? Like in this example, should i leave 'it' out?

The milk is very hot. The baby can't drink it now.
--> The milk is so hot that the baby can't drink it now.

Please tell me if the transformation above is correct or not. Thanks in advance and sorry for the bad English.

Answer

No, you shouldn't leave out the pronoun. Indeed, this is a good example of where pronouns are most useful.

We could have a similar use of so that didn't have a pronoun:

The milk was so hot that the baby was scalded.

We don't need a pronoun because we're not talking about the milk in the last clause, and while obviously the milk was the culprit we just haven't addressed that.

However:

The milk was so hot that the baby couldn't drink.

Is incorrect, because the milk's being hot doesn't make the baby incapable of drinking at all, just of drinking that particular milk. So we need to reference the milk again:

The milk was so hot that the baby couldn't drink the milk.

But this repetition of "the milk" is clumsy, so we use a pronoun to reference the previously stated noun, "the milk":

The milk was so hot that the baby couldn't drink it.

Really, the use of the pronoun has nothing to do with whether or not we use so + [adjective], but whether the following clause needs to refer to the noun again.