No, it's not improper.
Therefore, because it is not improper, one may begin a sentence with "therefore."
No, it's not improper.
Yes. There is no word or phrase that cannot begin an English sentence. For example: "However you slice it, this was a victory for our side." But when however means "all that other stuff notwithstanding," and is followed by a comma, good stylists do not begin a sentence with it.
this is not an improper sentence.
Starting a sentence with "for" is not necessarily improper, but it may make the sentence sound more formal or structured. It can be used to introduce a reason or explanation in the sentence. However, overusing it may affect the flow of the writing.
However is like but, and you can properly begin a sentence with it!
Understand the definition - improper means not proper. Then make a sentence When that kid sneezed, it was improper of him to not cover his mouth
It was quite improper for you to ask such a question.
"That was improper behavior" "Its quite improper to invite your self over"
He was scolded for his improper behavior at the formal dinner party.
In the sentence you love to stargaze, however tonight was too cold for enjoying the stars it is the improper use of voice.
The subject is improper for this forum. I got a citation for my improper left turn into oncoming traffic.