The word "as" can be used in various cases. Depending on a role in the offer and sense, the comma can face it. It is simple to remember such cases: in three the comma is put and in five is not put.
Instruction
1. First of all, the comma before the word "as" is put if this union is included into phrases which role in the offer is close to connective words. Treat them: "as if on purpose", "as a result", "as exception", "as a rule", "as always", "as now", "as now", "such as" and others. For example: In the evening, as if on purpose, the sun shone. Still example: And now he, as a result, is imprisoned.
2. If the union "as" is connecting between two parts of a complex sentence, then the comma is put. For example: I long thought how so it turned out that we were lost in the forest, knowing the road. Still example: It long watched how the fire burns down and in his eyes some grief pined.
3. If is present at the offer a circumstance which is expressed by a comparative turn, beginning with the union "as", then a comma it is necessary to put. For example: Her eyes were blue as the most clear sky. Still example: it was strong as a lion in a deadly fight.
4. It is worth paying attention that if after a turn with the union "as" the offer does not come to an end, then at the end of a turn it is necessary to put one more comma. For example: I distinctly heard how the child cries, but did not get up. Still example: she laughed as she the happiest person, and ran to me towards.
5. If the turn supporting the union "as" acts in the offer as an adverbial modifier of manner, then the comma does not need to be put. For example: he was uttered as the Englishman. In these cases the turn can be replaced easily with an adverb (in this case "in English"). In certain cases a turn is replaced with a noun in an instrumental case. Unfortunately, it is quite difficult to distinguish adverbial modifiers of manner from circumstances of comparison.
6. Also you should not put a comma if the union "as" is a part of a phraseological unit. However here it is necessary to be sure that this phrase is set. For example: he was in a chair before me on thorns.
7. If the offer without the union "as" does not make the finished sense and is a part of a predicate, then the comma also does not need to be put. For example: he keeps as a wolf. Also the comma does not need to be put if the word "as" is between a predicate and a subject. If this union was absent, then it would be necessary to deliver to a dash. For example: water as a mirror (water – a mirror).
8. If a comparative turn is faced by denial "not" or particles "simply", "exactly", "it seems", "absolutely", "almost", "absolutely", a comma you should not put that. For example, Harry had eyes exactly as at Lily.