【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成语还可再简化为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。