Place commas before and after D.C. (note the periods).
They went to Washington, D.C., to see a play.
One word, no hyphen.
Never abbreviate the names of the days in copy. Always capitalize days of the week.
They left on Thursday.
One word, with hyphen.
Use who for subjective case and whom for objective case. The following is a three-step rule of thumb for deciding whether to use who or whom:
1. Look only at the words that follow who or whom in the sentence.
2. Plug the gap in meaning with he or him, whichever makes sense.
3. Substitute who for he and whom for him.
Whom did you fire? ["Did you fire him?" (him = whom)]
The mayor, who reporters implied was dishonest, was silent. ["Reporters implied he was dishonest." (he = who)]
The suffix -wide is hyphenated only after a lengthy base word.
schoolwide (or, in the case of the Bloomberg School, Schoolwide)
For interdepartmental addresses, our Wolfe Street building is not designated Hygiene; it is known as Wolfe St. Bldg.
Wolfe St. Bldg., W1600
Web is capitalized in the Web and the World Wide Web. But: webcast, website, web page and webmaster are not capitalized (and are spelled as one word).
As a rule, we spell the following as one word, without spaces: