+378.+ Adjective clauses may also be introduced by _as_. _As_ is a very
convenient word and may be used in several different ways; sometimes as
an adverb, sometimes as a conjunction; and it may also be used as a
relative pronoun after _such_, _same_ and _many_. For example:
Such books _as_ you should read are listed here.
No such person _as_ he ever came here.
We are facing the same crisis _as_ our comrades faced.
This is the same _as_ you gave before.
He has made as many mistakes _as_ you have.
In these sentences _as_ is really used as a relative pronoun, connecting
these adjective clauses to the words which they modify. _As_ may also be
used as an adverb. _I am as tall as you are._
Here the first _as_ modifies _tall_ and is used as an adverb; the second
_as_ is a conjunction connecting the subordinate clause _you are_, with
the principal clause. Note that in making comparisons, _as_ is always
used when the comparison is equal, _so_ when it is unequal, thus:
I am _as_ tall as you are.
She is not _so_ tall as you are.
We have found that _as_ is also used as a conjunction to introduce an
adverb clause. For example:
She is as beautiful _as_ she is good.
The clause, _as she is good_, is an adverb clause, modifying the
adjective _beautiful_. In the sentence, _Do as I say_, _as I say_ is an
adverb clause of manner, modifying the verb _do_.