单选题 They can't help ______ of their daughter.
A. think B. to think C. thinking D. thought

【正确答案】 C

【答案解析】[解析] can’t help doing sth．是同定搭配，意为“忍不住做某事，情不自禁地做某事”，例如：She couldn’t help crying out at the news of her husband’s death．听到丈夫的死讯她不住放声痛哭起来。所以C是正确答案。