【正确答案】 A

【答案解析】[解析] cannot help but do=cannot help doing不由得，不能不，禁不住要。这个could not help but do短语还可再简化为could not but do，意思不变，如：I couldn’t help but overhear what he said=I couldn’t but overhear what he said=I couldn’t help overhearing what he said。