Good question, I have been wondering myself.
Until recently, yes, it was frowned upon, but in recent text it has become more acceptable;
much like the use of beginning a sentence with 'but'.
I hope that answered your question.
No, it's not improper.
Therefore, because it is not improper, one may begin a sentence with "therefore."
No, it's not improper.
this is not an improper sentence.
It was quite improper for you to ask such a question.
The subject is improper for this forum. I got a citation for my improper left turn into oncoming traffic.
Here are 3 examples:The book is improper for him.This movie is improper for the children.Why did you let her see this improper show?
The word 'is' can begin a sentence but not be a question when it is the subject of the question. Example sentence - Is can be the subject in a sentence. But only in sentences of that type (above) or, 'Is' is a two letter word. Otherwise is cannot begin a sentence.
Yes. There is no word that cannot begin an English 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.
It is very improper to talk with your mouth full.I would not want to set an improper example.
It is possible to have a sentence with the word it at the beginning, as this sentence proves.