作为情态动词时，两个词常用于疑问句和否定句；用作实义动词时，可用于各种句式．

1. 情态动词时：

例句：(1) ---Need I help you?

---Yes, please.

　　　　(2) You needn't telephone him now.

　　　　(3) How dare you talk to the teacher like that?

　　　　(4) The girl dare not go out alone at night

2. 用作实义动词时:

(1) We need to tell him the news.

Need (2) You don't need to tell him the news.

(3) Do the flowers need watering?

(4) I didn't dare to tell you the truth.

Dare (5) Would you dare to catch the snake with your hand?

(6) The boy dares to do anything he likes.

(II) shall

1. shall用于第一、三人称疑问句中，表示说话人征求对方的意见和向对方请示。

例句: (1) Shall we begin our class?（征求意见）

(2) When shall Mike be able to leave hospital?(请示)

2. shall用于第二、三人称陈述句中，表示说话人给对方的命令，警告，允诺，决心或威胁。

例句: (1) You shall go with me.(命令)

(2) You shall have the book when I finish it.(允诺)

(3) He shall be punished.(威胁)

3. 用于条约，规定，规章等文件中，表示一种义务，多用于第三人称中。

例句: "The interest ________be divided into five parts, according to the agreement made by both sides." declared the judge.

　(III) will

1. will表示请求，建议等，不如would委婉

例句: (1) Will /Would you pass me the book?

(2) Will you please close the window?

2. will 表示意志，愿望，决心

例句: (1) I will never do that again.

(2) I will give up smoking.

3. will 表示习惯性动作

例句: The couple will have a walk after supper every day.

4. 常用于否定句中，表示拒绝工作。

例句: The door won't open. 这门打不开。

（IV）used to 和would的区别

1. 都可以表示过去重复的习惯，used to 含有"过去怎样而现在却不这样了"的意思；而would则单纯表示过去的习惯性动作，常和often, everyday等连用。

例句: He would take a walk near the forest in the evening. （现在可能散步也可能不散步了）

He used to take a walk near the forest in the evening. （而现在不散步了）

2. 不可用would的情况：

例句: (1) She isn't what she used to be. 她跟过去不一样了。

（表示对比，不可用would）