副詞 without doubt:

1. admittedly
   同義詞：to be sure, no doubt
2. with certainty
   同義詞：undoubtedly, doubtless, beyond question, beyond any doubt

1. He is without doubt the cleverest student I've ever taught.
   他確實是我所教過的學(xué)生中最聰明的。
2. He is, without doubt, the greatest golfer in Japan.
   毫無疑問的他是稱霸日本的高爾夫球手。