Dare

It means "to have the courage to do something". In negative senteces it denotes lack of courage to do something. 

As a modal verb dare has two forms: dare for the present and dared for the past. It is used mostly in interrogative and negative sentences.

Examples:  
 She dare not open her mouth. (She hasn’t got the courage.)
 Dare he tell them what he knows? (Is he brave enough to tell them?)

Examples:  
 She dare not open her mouth. (She hasn’t got the courage.)
 Dare he tell them what he knows? (Is he brave enough to tell them?)

Patterns. Read and memorize! 

Affirmative 1	Interrogative	Negative
I dare say this.	Dare I say this?	I dare not say this.
She dare say this.	Dare she say this?	She dare not say this.
He dare say this.	Dare he say this?	He dare not say this.
We dare say this.	Dare we say this?	We dare not say this.
You dare say this.	Dare you say this?	You dare not say this.
They dare say this.	Dare they say this?	They dare not say this.

Note 1: - Modal verb 'dare' is mostly used in interrogative and negative sentences.

Note 2: – There is a contracted negative daren’t [deənt]. In British English, the negative 'daren’t' is frequent:
E. g. :  She daren’t tell the boss because she doesn’t want to make trouble.

The peculiarity of the verb 'dare' is that it is used both as a normal verb (taking the auxiliary 'do'in the interrogative and negative forms, -s in the 3rd person singular and a to-infinitive) and as an anomalous verb (like other modal verbs, without do, –s, and to ). As a normal verb it is usually used in the Past Tense.

Compare:

·       How did he dare to strike me? (normal verb) 

·       I did not dare to say a word. (normal verb)

·       How dare you interrupt him? (modal verb) 

·       We dare not remain here. (modal verb)

 ► As a normal verb 'dare' has a limited paradigm of finite forms and no verbals. It may have two meanings:   
1. To venture, to have the courage or impudence (like the modal auxiliary 'dare'). In this sense it is used mainly in negative statements:  

·       He didn’t dare to stop me. (He didn’t have the courage.)

·       She doesn’t dare to answer.

·       Don’t you dare to touch me. 

2. To challenge, to defy: 

·       I dared him to jump. (I challenged him to do it.)

·       'I dare you to climb on the roof, Bill!' said Larry.

Expressions with Dare

Note the following combinations with the verb 'dare'.

1. I dare say
 'I dare say' has almost the same meaning as 'probably' or 'I expect', 'I suppose', 'I think it is likely'.

·       I dare say you are right. 

·       I dare say he will come later.

·       It’ll rain tomorrow, I dare say. 

2. How dare you (he, she, etc.) do something  = How can you (he, she, etc.) be so rude and bold = I am very surprised and shocked by what you are doing.

·       How dare he speak to you like that? (I wonder at such impudence.) 

·       How dare he accuse me of lying!

·       How dare you listen to a private conversation? 

3. How dare you? - we use this as an indignant exclamation.

·       How dare you? Take your hands off me at once! (How can you be so bold?) 

4. You dare! / Don’t you dare! – these expressions are used to discourage people from doing things they shouldn’t (for example by mothers):

·       'Mummy, can I draw a picture on the wall?' – 'You dare!'

·       I'll tell her about it. - Don't you dare! 

5. I dare you to do something – this expression is used (for example by children) to challenge each other to do frightening things.

·       I dare you to ride your bike through the gate with no hands. 

·       I dare you to jump the stream! 

6. Dare someone to do something - we use this expression to challenge someone to do something to see if he is brave enough to do it.

·       Sally dared Jane to race her to the corner. You wouldn't do that, would you? I dare you.

Reference:

1. English Grammar