长破折号（—）比连字符（-）和短破折号（–）长。
要打出长破折号，您需要按ALT 0151。如果这个快捷键无效，您也可以用打字方式产出长破折号，输入两个连字符后，不加空白直接打任意字即可，例如：“see” 两个连字符 “this”，您会得到 “see—this”。如果您想要在长破折号的两边加空白，回过头输入即可。
长破折号是文学格式符号，在使用上很多时候不是必须的，因此它取决于使用者的习惯和偏好。我只想得到一个必须使用长破折号的情景，如以下“规则”所述，其余的则是非必须的“选择”性使用。
不要过度使用长破折号，不然效果会打折。
什么时候可以用长破折号？
用于表示被他人打断谈话或讲话的人自行中止发言时
“You just haven’t been listening. I told you—” “No, you aren’t listening to me.”
“Why did she—oh never mind, it doesn’t matter.”
用于对话中的动作顿点
“Wait! I need”—Mark looked down and cleared his throat—“um, well, here, you forgot this.”
使用逗号代替长破折号是不正确的；然而，可以用句号将之分成两句：
“Wait! I need…” Mark looked down and cleared his throat. “Um, well, here, you forgot this.”
使用长破折号来强调语气，为了将焦点放在框起来的部分
My son is now a scholar—nearly in the 90 percentile—so you wouldn’t know by looking at him that he used to be failure to thrive.
一般来说，括号的用途更常用于补充、澄清或对句中主题的评论，而不作为强调使用。长破折号则能凸显框起来的信息，使其更为显眼。
使用长破折号于分隔已经包含逗号的修饰词组
If you need to get a hold of me quickly, try email first—my work email, not my personal one—and I’m more likely to see it sooner than a text.
注：这句可以因想要强调其中的内容而加上破折号，合情合理，毕竟强调“用哪个账号来联系”很重要。然而，在这种结构中，作者之所以选用破折号不是因为想要强调框起来的文字，而是因为句子包含数个逗号。因此，破折号可避免频繁使用的逗号，来增进句子的可读性。
使用长破折号，而不是冒号，来做解释说明的用途
Many jobs interest me—teaching, editing, public speaking, and tutoring.
There was a clear reason for a drop in attendance at NBA games this season—there was no superstar to take the place of Michael Jordan.
之所以使用破折号而非冒号，是因为加强强调长破折号框起来的部分。
练习：
我们提供一些练习来助您掌握长破折号的使用方法。请您使用长破折号来改写以下句子；其中一则不需用到长破折号，看看您是否能找出来。
- “Yes, I think we . . . Xiao Ming, don’t touch that. Sorry I need to go get my son.”
- Most of my family members, my brother, his wife, my sister, her husband, and my mom, came with us.
- Mark Alma Lunduqist, born in 1978, became the head doctor.
- Save the Cat is one of the few books, actually, the only book, you’ll ever need on craft.
- I bought several clothing items, all of which were on sale, since I have changed size.
- “Don’t you think” Chen rubbed his eyes. “I mean, it’s what I would do.”
- Chang has one golden rule for dealing with money: “Never a borrower nor a lender be.”
- “Why do you think . . .” “Shhh. Don’t talk!”
解答：
- “Yes, I think we—Xiao Ming, don’t touch that. Sorry I need to go get my son.”（讲者自行中断自己的谈话）
- Most of my family members—my brother, his wife, my sister, her husband, and my mom—came with us.（框起来的部分包含逗号，长破折号有助增进可读性）
- Mark Alma Lunduqist, born in 1978, became the head doctor.（不要加长破折号；这个信息会放进括号，而非逗号之间，因为这是补充信息，不需要特别强调）
- Save the Cat is one of the few books—actually, the only book—you’ll ever need on craft.（框起来的部分很重要，因此用长破折号加以强调；另外，框起来的部分还包含一个逗号）
- I bought several clothing items—all of which were on sale—since I have changed size.（对话者很担忧花掉的钱，对此加以强调是合理的）
- “Don’t you think”—Chen rubbed his eyes—“I mean, it’s what I would do.”（对话中途的动作停顿）
- Chang has one golden rule for dealing with money—Never a borrower nor a lender be. （做解释说明）
- “Why do you think—” “Shhh. Don’t talk!”（谈话被他人打断）
