動詞 doubt:

1. consider unlikely or have doubts about
   同義詞：doubt
2. lack confidence in or have doubts about
   同義詞：doubt

形容詞 doubting:

1. marked by or given to doubt
   同義詞：questioning, skeptical, sceptical

1. He doubts if the officer is anybody.
   他懷疑這官員是個要人。
2. I doubt the truth of it.
   我懷疑此事的真實程度。
3. There is no doubt that we will be successful.
   毫無疑問我們會成功的。
4. There is no doubt about it.
   那是毫無疑問的。