certain的副詞是什么意思

　　'Certainly not,' he replied emphatically.

　　“當然不。”他斷然回答道。

　　Moby certainly has a fine ear for a tune.

　　莫比對音調的分辨能力一定很強。

　　He certainly was not politically inactive.

　　他在政治上當然不是無所作為。