Grammatically Correct: The writer's essential guide to punctuation ...

PUNCTUATION
Aside from the impact on meaning that the colon can confer,
note how it offers some stylistic advantages by allowing you to run
choppy sentences together, thereby achieving a better flow, and
sometimes allowing you to drop a few words, thereby making your
writing more concise.
OTHER USES OF THE COLON
The colon has a few mechanical applications, as described below.
SEPARATING THE NUMBERS IN A RATIO
4:1 3:2
Note that if you were writing these numbers out as words rather
than numerals, you would use the word to instead of a colon: jour
to one; three to two.
SEPARATING THE HOUR FROM THE MINUTES
1:30 5:45
Note that the British style is to use a period instead (1.30; 5.45).
SEPARATING A MAIN TITLE FROM THE SUBTITLE
The Fatal Shore: The Epic of Australia's Founding
"Universality and variation in moral judgment: A longitudinal and cross­
sectional study''
SEPARATING LEAD-IN TEXT FROM
SPOKEN WORDS IN DIALOGUE
The uproar subsided, and I tried again: "Ladies and gentlemen!"
He suddenly turned to her and said: "Why me?"
Similarly, it may be used instead of a comma to introduce a
quotation.
SEPARATING LOW-LEVEL SUBHEADINGS AND FIGURE OR
TABLE IDENTIFIERS FROM THE TEXTTHATFOLLOWSTHEM
The Colon: The colon has the following functions ...
Figure 12: Diagram of developmental diversity.
Alternatively, a period or a closing parenthesis may be used.
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