You must read the book, as must your brother.
I want to use this sentence to express the following meaning:
- Your brother must read the book;
- You also must read the book like your brother.
Is it natural?
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Sign up to join this communityYou must read the book, as must your brother.
I want to use this sentence to express the following meaning:
Is it natural?
This sentence is grammatically correct, and unambiguously expresses your intended meaning. To my (American) ear, it sounds like a nineteenth-century novel. It does not sound natural to me. "As must" is now rarely used.
To my English ear
"You must read this book, as must your brother"
might easily and naturally be spoken by a parent forcefully emphasising to each sibling individually and without ambiguity that neither of them has a choice...
(Looking at one child) "You must read this book,..." (turning to look at the brother) "...as must your brother!"
It's correct, but sounds a bit old-fashioned or academic.
A more usual way of saying it would be "You have to read the book, and your brother does too."