I'm surprised at someone so rich _____ difficulty in paying what he owes you．A）as to haveB）who has noC）havingD）that he has no

从意思理解上选择。my opinion

I'm surprised at someone so rich _____ difficulty in paying what he owes you．A）as to haveB）who has noC）havingD）that he has no

surprised说明奇怪，说明不合理
有钱 却 不还债 所以奇怪
所以不能说 no difficulty
having difficulty 作为 状语修饰someone so rich

having difficulty in doing sth

读起来c最通畅哈哈，道理就不懂了

这里考察的是动名词做宾语补足语的语法，havingd短语补充说明at 的宾语someone的补足语，补充说明为什么I 对so rich的一个人（someone）感到吃惊的原因

选择D答案是错误的，so…that… 结构通常引导结果状语从句，但是rich 不是造成have difficulty 这个结果的原因，所以，不能用。这里考察的其实是动名词短语的复合结构：someone (so rich) having difficulty … 。someone做介词at 的宾语，having 短语则是吃惊的内容，因为“ so rich”的人 having difficulty 而感到吃惊，someone 是动名词having 这个动作的逻辑主语。就是说having 这个动作是由someone支配的，having difficulty 是 someone 这个宾语的补语。所以答案应该选C。

RICHARD d解释完全正确，就是代名词做宾语补足语

1.一般来说“我很惊讶”是因为“一个富人欠我钱”；再者，用who/that 引导定语从句，其后不需要跟先行词he，所以不可能选择D

2.A/C句意上符合，A中的as to作用有：1.置于句首表示强调2.表示旧事重提3.置于句中提出问题（后＋wh-/who-to-v.结构）4.按照，根据
C使用动名词作后置定语，表示主动、进行

d不符合语境
d ：我很吃惊，有人如此富有，以至于还你钱毫无压力。
C  ：我很吃惊，有人如此富有，但却不肯还你钱。
你觉得哪个更值得吃惊？

The correct answer is C) having.

The phrase "I'm surprised at someone so rich having difficulty in paying what he owes you" is a idiomatic way of expressing the idea that the person is wealthy and it's unexpected that they would have difficulty paying what they owe.

Choice A, "as to have" is not idiomatic and does not convey the same meaning as the original sentence.
Choice B, "who has no" implies that the person does not have difficulty in paying what they owe, which contradicts the idea that the person's wealth makes it unexpected that they would have difficulty paying.
Choice D, "that he has no" is not idiomatic and does not convey the same meaning as the original sentence.

不是这么有钱以至于还不了钱，而是这么有钱却还不了钱