1. When an adverbial clause follows-the principal clause, no stop is generally used. When it precedes the principal clause, it is separated from it by a comma.
The solicitor addressed me as he descended the stair. (Ch. Bronte)
He sank into a silence so profound that Aunt Hester began to be afraid he had
fallen into a trance. (Galsworthy)
He drew the blanket over his head that he might not hear. (Voynich)
When Phyl called to see how Pearl was getting on, she found her still curled
up sulkily in her arm-chair. (Lindsay)
Though I had now extinguished my candle and was laid down in bed, I could
not sleep. (Ch. Bronte)
If any shareholder has any question to put, I shall be glad to answer it.
2. An adverbial clause of result coming after the principal clause, which is usually the case, is often separated by a comma.
The thicket was as close as a brush; the ground very treacherous, so that we
often sank in the most terrifying manner. (Stevenson)
§ 18. If in a complex sentence there are two or more homogeneous clauses, they are separated from each other by a comma.
When dusk actually closed, and when Adele left me to go and play in the
nursery with Sophie, I did not keenly desire it. (Ch. Bronte)
§ 19. At the end of every kind of declarative non-exclamatory sentence — simple, compound, complex, and compound-complex — a full stop is used.
Young Jolyon poured out the tea. (Galsworthy)
All the life and expression had gone out of his face; it was like a waxen mask.
They turned back towards the bridge over which the Cardinal’s carriage
would have to pass. (Voynich)
§ 20. At the end of a sentence expressing a question, real or rhetorical, a note of interrogation is used.
Do you recognize that letter? (Voynich)
Is this a dagger that I see before me? (Shakespeare)
A note of interrogation is used at the end of sentences containing questions even if the order of words is that of an affirmative sentence.
And he wants you to live on cocoa too? (Galsworthy)
You deny that it is in your writing? (Voynich)
§ 21. At the end of exclamatory sentences a note of exclamation is used.
It’s a lie! (Voynich)
What a beautiful voice that man has! (Voynich)
§ 22. To indicate a sudden stop in the thought a dash or two dashes are used.
Oh! how I wish — But what is the use of wishing? (Fowler)
“Oh, well,” he said, “it’s such a long time since — ” He faltered. He stopped.
It should be noted that the use of most stops largely depends on the will of the writer.