"I don't know exactly," replied the doctor in a dubious tone.
"Why—I've never worn a low dress—not really low," I said, longing but dubious.
Better that he had been still silent, than speak that dubious, indecisive "Y—es."
Mr. Cruncher was soothed, but shook his head in a dubious and moral way.
They liked him, but they were dubious of his right to represent the Tory spirit.