Nineteen billion, six hundred seventy-three million, eight hundred ninety thousand, ninety-four.
There are no hyphens in the word ago.
Hyphens are used to link words together to form compound words, such as "well-being" or "mother-in-law." They can also be used to separate syllables in words that are broken at the end of a line in writing. Additionally, hyphens are used in some prefixes, suffixes, and to avoid ambiguity or confusion in writing.
hyphen
They are considered as one word.
sisters-in-law
The word "affection" does not require a hyphen.
path-oecologist
Because hyphens are dashes. Word changes double dashes into em dashes (the long dashes) automatically if there is a space before and after the double dash.
Not necessarily. There is no word or phrase in English that requires a comma.
Sister-in-law. With the hyphens, it's one word. : )
The use of hyphens is called hyphenation. A hyphen ( - ) is a punctuation mark. Hyphens join words and separate syllables such as in the word sleeping-bag.
Errm... Inverted commas?