难怪 (nánguài) when used as a verb can be translated as "hard to blame." This is usually directed at a person, and it is similar to how in English we may say "He's always sleepy, but you can't blame him because he works a night shift."
难怪 as a Verb
Structure
难怪 + [Specific Person / People]
When used as a verb it expresses that the speaker assigns no blame in the situation he is describing i.e. that someone is not to be blamed. Often a person is placed after it, as in the latter two examples below.
Examples
- A: 他 迟到 了 。A: He's late.
B: 这 也 难怪。 今天 地铁 坏 了 。 B: Don't blame him, the subway broke down today.
- 难怪 他，他 还 是 个 孩子 呢，什么 都 不 懂。 Don't blame him, he's just a child. He doesn't know any better.
- 这 也 难怪你，第 一 次 到 这 个 地方 还 不 了解 这里 的 风俗。 No one can blame you, the first time I came here, I didn't understand the customs.
- 这 也 难怪，他刚来嘛，算了算了。 Don't blame anyone, he just got here, forget it.
See also
Sources and further reading
Books
- 现代汉语八百词（增订本） (p. 239) (p. 408)
Dictionaries
- 现代汉语词典（第5版） (p. 499) (p. 981)