"also must"

[salvador.dal1950]

Is it correct to use "also" next to "must". For example in the following sentence:

New words are necessary because, as the world changes, so must our vocabulary.

Could I replace that "so" with "also"? I know that the sentence sounds better with "so", at least to my ear.

Thank you :up:

 

[emsr2d2]

If you swap "so" for "also", I would change the word order.

... so must our vocabulary.
... our vocabulary must also.

I find the second version far less natural.