有人问： 有这样一个句子：

(1)The window was open only a crack.

如何分析这里的a crack?

a crack是一名词短语，在此用作状语，修饰表语open，再如：

(2)Open the door a crack .

(3)She opened the door just a crack to listen to the conversation.

(4)When she opened her bedroom window a crack she could hear the angry sea below, crashing against the rocks.