Pushing something too far.
9 and if you really want to push the envelope 10 ...just a little humor....10
It means you are stretching the borders. You are doing things with something that wasn't originally intended to be done.
The answer is an envelope. It contains a letter.
Envelope is a noun.
It does
The word is "envelope" (which usually holds only one letter).
on the envelope.
This envelope is like the window envelope,but the window opening is uncovered (an uncovered address panel).
The prepositional phrase in the sentence is "on the envelope".
The possessive form for the noun envelope is envelope's.Example: The envelope's flap wasn't sealed.
When sending a wedding invitation the response card should go into the response envelope and you should address it back to you on the front of the response envelope with a stamp on the envelope.
Envelopes is correct.