系动词 to be, 助动词 do(does), have(has), shall(should), will(would) 以及情态动词在句中一般是不重读的。但是它们在以下几种情况下是有句子重音的：
1.）在肯定陈述句中表示强调时，例如：
She 'is a doctor.
l 'am a student.
They 'are students.
He 'has done it.
l 'have told you before.
l 'shall come.
He 'will do it.
l 'can do it.
He 'may be there.
2.）和否定副词 not 连写成简缩式 aren't, isn't, don't, doesn't, haven't, hasn't, shan't, shouldn't, won't, wouldn't 和 cannot, can't, mustn't 时，例如：
They 'aren't students.
He 'isn't a doctor.
'Don't open that window.
He 'doesn't have a red pencil.
They 'haven't come yet.
He 'hasn't written the letter yet.
l 'shan't go today.
He won't come with me.
l 'cannot speak Spanish.
He 'can't come today.
You 'mustn't do that.
3.）在句尾代表整个谓语部分时（如在普通问句的简略答语中），例如：
Are you a student? ——Yes, l 'am.
ls she a nurse? ——Yes, she 'is.
Do you have an exercise-book? ——Yes, l 'do.
Does John have a pen? ——Yes, he 'does.
Have you seen him today? ——Yes, l 'have.
Has he come yet? ——l thank he 'has.
Will you call on them today? ——Yes, l 'shall.
Can you speak English? ——Yes, l 'can.
4.）在问句的句首（此情况也可弱读）和表示惊讶、好奇、忧虑等的问句中，例如：
'ls he a teacher?
'Do they have exercise-book?
Where 'does he work?
'Have you ever been to Hongkong?
What 'have you done?
'Shall we have a group discussion today?
What 'shall we do about it?
'Can you speak French?
'Must l say it in EnglishA?
What 'can we do about it?
感叹句的重音：
what 和 how 一般都有句子重音，例如：
'What 'lovely 'weather we are having!↘
'How 'happy we are!↘
'How 'hard they work!↘
但 what 在下列省略句中不重读，以突出强调它后面的 beautiful 这个词：
What 'beautiful weather!↘
