◆To me, the story of the Terracotta Army is almost unbelievable.

用 to 还是 for，这与形容词的搭配、以及同一个形容词的不同词义有关。与位置没有关系，我把语序调整一下：

The story of the Terracotta Army is almost unbelievable to me.

这里，to 表示“对象关系”，意为“对某人而言”，重在表达看法。

unbelievable 接 for，也是可能的。比如，这项工作太难了，让一个孩子去完成，简直难以置信。可以这样说：This difficult job is unbelievable for a child. 这里，for 表示是否“适合，胜任”的意思。

以下是我之前的一个解答，也许对网友这个问题，有一定的启发。

◆学生问：有一次见到一本教辅书上讲，像useful, important, necessary这些词一样，good之后用介词to或for没有区别，可以互换。请问老师，这样说对吗？

这种说法是不对的。因为good有不同的含义，所使用的介词也不尽相同，而且to和for的意思也有差别。good在句中用作表语时，接to表示“仁慈，善良，友好，和蔼可亲”；接for可表示“有效的；合适的；胜任的”。如果表示“有益处，有好处”，用 to 或 for 均可。

下面，我们先看一个英语幽默故事：

A man was troubled by mice. They ran about all over his house at night. In the daytime, they just stayed under the floor.

The man thought, “What I need is a cat, a good cat that can catch mice.” He knew of a man who had cats for sale. So he went to see him. “Do you have a cat that is good for the mice?” he asked the man. “Well, yes. I do happen to have a cat that is good to the mice,” replied the man. “I’ll take it,” said the first man.

He paid for the cat and took it home. A week later, the cat didn’t catch any mice, but it played with them like old friends. So the man went back again with the cat under his arm. They had a quarrel because they both took the meaning of “good” as they needed.

上面的故事十分有趣。买猫人是想买一只good for mice的猫，然而，那个卖猫人有一只good to mice的猫，最后结果必然是一场quarrel。

下面，我们分析一下故事中的两个关键句子：

“Do you have a cat that is good for the mice?”

“你这儿有没有胜任捉鼠的猫？” 

“I do happen to have a cat that is good to the mice.”

“碰巧我还真有一只对老鼠不错的猫。”

good表示“有效，胜任，适合”意思时，用be good for；good表示“仁慈，善良”意思时，用be good to。只有表示“对......有益处”时，两者可以互换。试比较：

1. 仁慈，善良，友好：

The old lady is good to the boys.（正确）

The old lady is good for the boys.（错误）

2. 有效：

The medicine is good to the disease.（错误）

The medicine is good for the disease.（正确）

3. 合适（匹配）：

The gold chain was just good to Jim's watch.（错误）

The gold chain was just good for Jim's watch.（正确）

4. 胜任：

John is not good to the job.（错误）

John is not good for the job.（正确）

5. 有益：

Athletic sports are good to your health. （正确）

Athletic sports are good for your health. （正确）