dark 与 darkness

dark（名词）和darkness的用法没有绝对的区别，但下面几点该注意：

（1）只有dark可以指“傍晚”，at dark，before dark和after dark里的dark不可改作darkness，前面都没有the。

（2）in the dark在用作“不知道的”解的时候dark不可改作darkness。例如：I am in the dark about his whereabouts.

（3）The room is in darkness里的darkness不可改作dark或the dark。

（4）dark惯用在指经常的情况，darkness惯用在指一时的情况。例如：

• Some children are afraid of the dark.
• He stayed behind because he was afraid of the darkness.
• We set off in the darkness across the flat county.
• I could not see the house properly because of the darkness.

但in the dark一语也往往指一时的情况，例如第三句里的darkness可以改作dark。