certainly为副词,用在动词前.比如说： He certainly tells me the truth of that matter.
am为系动词,后面应跟形容词,当然是certain. 比如说：I am certain that he is a brave man.
certainly为副词,用在动词前.比如说： He certainly tells me the truth of that matter.
am为系动词,后面应跟形容词,当然是certain. 比如说：I am certain that he is a brave man.