arorag wrote:I am interested to know rule of verb placement in following comparison.

what are differences in following three sentences

X have Y as do Z
X have Y as Z do

"as do Z" is ALWAYS correct.

"as Z do" is only correct if Z is NOT FOLLOWED BY AN ADJECTIVE TYPE MODIFIER.

here are illustrations:

rhinoceroses have horns, as unicorns do.
rhinoceroses have horns, as do unicorns.
both correct.

rhinoceroses have horns, as the fabled unicorns of mythology do.
incorrect. in this case, "do" is separated from "unicorns" by the modifier. that's unacceptable.

rhinoceroses have horns, as do the fabled unicorns of mythology.
correct.

--

X have Y as Z

this is wrong. you can't use "as" in a comparison, unless it's followed by a CLAUSE (i.e., there has to be a verb).
in this case you've omitted the verb, so this is a no-go.

on the other hand, you could quite easily replace "as" with "like":
X have Y, like Z
or, better,
like Z, X have Y
these are correct.