indubitably
  (ad.)無疑地;確實地
  In·du·bi·ta·bly, adv. Undoubtedly; unquestionably; in a manner to remove all doubt.
     Oracles indubitably clear and infallibly certain.   --Barrow.
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  indubitably
       adv : in a manner or to a degree that could not be doubted; "it
             was immediately and indubitably apparent that I had
             interrupted a scene of lovers"