As mentioned earlier, when the rod is only one, we don't know
whether the rod is long or short.
To know it, we should compare
the rods relatively.

If we don't decide an absolute standard of these units, then the rod B is equal
to one.
In mathematics, If A*B=A, B*A=A , then B=1.
The every unit must
have an absolute standard, but if the units don't have it, the denominator must
become one.
Until now, mathematicians don't have explained " why the
denominator cannot be zero?"
Using the length principle, this problem is
easily solved. Physicists have passed over this point.
Therefore, the unconsciousness of the absolute standard must become one.