dubious

/ˈdʒuː.bi.əs/

thought not to be completely true or not able to be trusted

半信半疑的，可疑的;不确定的;不可信的

These claims are dubious and not scientifically proven.

这些说法未经科学证实，有些可疑。

She knew he really wanted to help her; however, she was dubious about his ability to help.

她知道他是真心想帮她，但对他有没有那种能力却半信半疑。