Translation of "Skeptical" in Japanese

He was encouraging but a bit skeptical.

応援してくれましたが ちょっと慎重でした

He is more skeptical than I am.

あいつ俺より疑い深いからな。

That’s why Cocks is skeptical of stories claiming unprovoked and revenge group attacks.

コックスいわく 集団攻撃を するというのは作り話です

- I'm dubious about claims to speak more than five languages fluently.
- I'm skeptical when I hear someone claim to speak more than five languages fluently.
- I don't quite believe it when I hear someone claim they can speak more than five languages fluently.

私は、5つ以上の言語を流暢に話せるという主張には、疑いを持ちます。