This section will be expanded at intervals.
"Travis tricked us," said Jenna.
Although 'Travis tricked us' is a complete sentence, when it is followed by 'said Jenna' or equivalent thereof, the full stop at the end of the sentence is replaced by a comma and 'said' will have a lower case 's'.
"Where are we going?" asked Cally.
When the original sentence ends in ? or ! these are not replaced by commas, but 'asked' still begins with a lower case 'a'.
Where the words that follow the speech are not a description of the speech, the rule is different.
"I'm working on it." Avon bent over the console.
This sentence retains the full stop.
Splitting sentences in speech.
"I'm leaving," Avon said, "and I'm not coming back."
"I'm leaving and I'm not coming back." is one sentence, so there is a comma after 'leaving' and a comma after 'said'.
"Why?" demanded Blake. "Where would you go anyway?"
'Why?' and 'Where would you go anyway?' are two separate sentences, therefore there is a full stop after 'Blake'.
"Shoot, Vila!" shouted Avon.
"Shoot Vila,!" shouted Avon.
These two sentences are very different. In the first, Avon is telling Vila to shoot; in the second, he is telling someone else to shoot Vila. The key difference lies in the comma before the name. When speech us being addressed to a person, there should always be a comma before their name. eg. "You're a fool, Blake".
Their means 'belonging to them'. eg. "That is their problem."
You're is an abbreviation for you are. eg. "You're going on this expedition."
The ship belongs to Blake; it is Blake's ship.
Things may belong to individuals or to groups.
The mutoid's blood. In this case, there is only one mutoid and the apostrophe goes before the s.
The mutoids' blood. In his case, a group of mutoids are apparently sharing a blood supply, and the apostrophe comes after the s.
The words his, her, its and yours are used to indicate possession as well. Note that when its is used in this context, there is NO apostrophe.
After Orac takes its turn at Galactic Monopoly, it will be Dayna's turn.
Apostrophes are used to show where letters have been omitted in abbreviations.
It is Blake's turn. It's Blake's turn.
I was not there. I wasn't there.