Here are examples of the word/phrase "dubious" used in a sentence and paraphrased in a sentence...
I was somewhat dubious about whether or not I could reach the top of the mountain.
I was somewhat doubtful about whether or not I could reach the top of the mountain.
Due to my good credentials, I was not dubious about getting the job.
Due to my good credentials, I was not skeptical about getting the job.
Other Examples...