looking back on it是整个句子的状语.宾语从句是用IT做形式主语,真正主语是 to put more time and energy into studying,估计你是would have been better 不明白,这里是一种虚拟,表示对过去事实的一种惋惜.
looking back on it是整个句子的状语.宾语从句是用IT做形式主语,真正主语是 to put more time and energy into studying,估计你是would have been better 不明白,这里是一种虚拟,表示对过去事实的一种惋惜.