Expressing Uncertainty:
* "I'm doubtful about the accuracy of that report."
* "The chances of success are doubtful at best."
* "He was doubtful whether he would be able to finish the project on time."
Expressing Skepticism:
* "I'm doubtful that she's telling the truth."
* "He looked at me doubtfully when I told him the news."
* "The evidence is doubtful and needs further investigation."
Describing a Situation:
* "The future of the company is doubtful."
* "His recovery is doubtful after the accident."
* "The weather forecast is doubtful, so we might have to postpone the picnic."
In a Negative Context:
* "It's doubtful that he'll ever recover from his injuries."
* "The chances of finding a cure are doubtful."
* "The outcome of the negotiations is doubtful."
In a More Formal Context:
* "The doubtful nature of the evidence led to the case being dismissed."
* "Her testimony was doubtful and contradicted by other witnesses."
* "The validity of the experiment is doubtful due to methodological flaws."
Remember:
* "Doubtful" can be used as an adjective or an adverb.
* It often expresses a sense of uncertainty or skepticism.
* You can use it in various contexts, from casual conversation to formal writing.