Dr. Bill's notes:
You might notice a very slight forward movement as the "S" changes
into a "D." This is not a conscious thing. It is just a
natural aspect of activating the muscles to change the "S" handshape
into a "D" handshape. If I were you I wouldn't "try" to do that
micro forward movement, just focus on spelling "S" and "D" and
you'll notice it happening naturally.
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