※ 引述《sobi513 (bumpy)》之铭言：
: 下图中第15题的答案，我想破脑袋都无法解析该句以及不懂为何答案会是“to have been”
: 。
: https://i.imgur.com/id0jyrQ.jpg
: 第一次发文求助，若发文格式或内容违反版规，烦请告知，我会尽速修正，谢谢！
All the spectators buzzed noisily and everyone craned their neck to witness
what this man looked like ______ bold enough to seduce a princess.
首先说明答案 (C)
(C) to have been
■ 根据前后文，本句的句意应该是“所有观众都闹哄哄，每个人都伸长了脖子，想看看
这个人是什么样子的，竟然敢勾引公主。”
因此判断原始的句子应该是用表“结果”的从属连接词连接的副词子句：
All the spectators buzzed noisily and everyone craned their neck to witness
what this man looked like [so that he had been] bold enough to seduce a
princess.
[...] 里的动词时态，可以用过去完成式，与前面的过去式动词 buzzed, craned 等构成
先后时间的比较。而在实际写作上，可以用过去式替代过去完成式。但是由于本题最后答
案是完成式形式，所以目前采过去完成式。
■ so that + clause 为副词子句，可以用来表目的或表结果：
1. with the aim that; in order that 为的是；以便：
She worked hard so that everything would be ready by 6 o'clock. 她拚命干以便能
到 6 点时把一切都准备好。
2. with the result that; to the extent that 结果；以致；因此：
Nothing more was heard from him so that we began to wonder if he was dead. 再
也没听到他的消息，因此我们有些怀疑他是否死了。
目前依据原文语意，应该采取表结果的用法。
■ 表结果的副词子句可以简化为表结果的不定词词组：
so that he had been bold enough to seduce a pricess
-> to have been bold enough to seduce a pricess
■ 若从上下文中可明确看出所指之人时，不定词词组的意义上主词可以省略不写，如本
题中原本 so that he 中的 he 在不定词词组中被省略。若担心语意不明的话可以加上
for him [to have been]
综合以上说明，(C) 可以选为答案。