My friend,i'll tell u the how to tell.
如书上写的：I didn't dare to open the window until the window had to be shut.
这里的dare便是实意动词,为vt.及物动词.
1.情态动词dare 没有人称的变化.
2.情态动词dare 通常用在否定句中.
3.如果是实义动词问,回答也用实义动词.
4.I did’t dare (to) speak to him again.= I dare not speak to him again.
dare do 是情态动词
dare to do是实义动词
..not dare ...是实义动词He didn't dare ...
...daren't 是情态动词 He dared not ...