The single quotation mark in front of the null list is used to tell Scheme that you are using as data and not as a part of your parse tree.
空列表前面的单引号用来告诉scheme您正在使用作为数据，而不是用它作为解析树的一部分。
2
Some of what she cut out of the poem, cut out of its later version, is a listof what she had in mind as the genuine, as examples of it, which is the first quotation there; again, on your handout.