as作为介词可以单独使用，这里不再赘述；as作为介词还可以和其他词一起组合，从而构成介词短语，如：as against、as for、 as of、 as regards、as to等，用这些短语介词构成的短语可作状语。
They were all dressed as clowns.
The bomb was disguised as a package.
She works as a courier.
Treat me as a friend.
I respect him as a doctor.
You can use that glass as a vase.
The news came as a shock.
She had been there often as a child .
2. as against sth
They got 27% of the vote as against 32% at the last election.
Over 50% of divorced men regretted their divorce, as against 25% of women.
The earth is small as against the sun.
3. as for sb/sth
As for Jo, she’s doing fine.
As for doctors, when you go to see them they just look right through you.
As for your father, he won’t be mentioned in my will.
As for Laura and me, the colour of our skin has never mattered
As for you, I don’t think you have to go in person.
As for India’s nouveaux riches, they will now have to pay still higher duties on luxury goods.
The nouveau riche have to find a way to be accepted
As for food for the party, that’s all being taken care of.
As for avoiding you, nothing could be further from my mind.
As for his job — well, he was very mysterious about it.
As for anything told to me in confidence, well, my lips are sealed.
As for her engagement with Adam, I would say the portents are gloomy.
As for the present, things are far better than at any time in the past.
As for the subjects that so enrage puritans, they will continue to form the focus of her work.
4. as of作为
Education is provided by the state as of right.