高中英文As expected & As usual的省略

1. "as" when used as conjunction:

e.g. As it is expected, [ main clause ].
"as" means " in the way in which"

"it" is a dummy pronoun, representing the event of [ main clause ] itself. Therefore, the dummy-it or together with the verb-to-be can be dropped in a reduced format, as:
As is expected, [ main clause ].
As expected, [ main clause ].

--- both sentences are correct ----

2. "as" when used as adverb, it is usually placed in front of another adverb or (adverbial) prepositional phrase to say that something happens in the same way:

e.g. As always, he said little.
e.g. The ‘h’ in honest is silent, as in ‘hour’.

3. Idiomatic expressions:
The following expression are idioms but not a reduction.

as always
= as usually happens or is expected

as usual
= in the same way as what happens most of the time or in most cases

2015-01-05 01:07:46 補充：
補充： more examples on 1./ conjunction

Do as I tell you! (active voice)
Do as you are told! (passive)
Do as told! (reduction)

The money was repaid, as I promised him. (active)
The money was repaid, as he was promised. (passive)
The money was repaid, as promised. (reduction)