a. Use a dash to link two parts of a sentence.
Okay: Always buckle your seat belt; it's the law.
Stronger: Always buckle your seat belt—it’s the law.
b. Use a pair of dashes to emphasize by-the-way, parenthetical expressions.
*My grandmother bought me a puppy—an adorable little bulldog!—for my birthday.
*I’ve lived in Portland—the one in Oregon, not Maine—all my life.
c. Use a dash to set off a long appositive (a description of who or what the subject is) or an appositive with lots of commas.
例句：My best friends—Amani, Catherine, Erin, Kai, and Lola—are here.
d. Use a dash in dialogue to show hesitation or a break in the flow of the sentence.
例句：Esperanza said, “I definitely studied enough for the test—or I think I studied enough—I probably studied nearly enough—well, I hope I studied enough.”
e. Use a dash to sum up a list or idea.