By underscoring the words with two lines.
31. How are written words marked that are to be printed in Italics?
By underscoring the words with one line.
32. When use the Interjection O?
The letter O is a vocative particle, and should always be used before nouns or pronouns in the absolute case by direct address.—[Ridpath.]
33. When use Oh?
In all cases where it is not followed by nouns, or pronouns, in the vocative case.—[Ridpath.]
ABBREVIATIONS.
1. What is an abbreviation?