dubious

这一理论的证据充其量是值得怀疑的。

The evidence for this theory is ___dubious at best.

他在业内以名声可疑而闻名。

He is known in the industry for having a ___dubious reputation.

他对宣称的这种新饮食趋势的好处持怀疑态度。

He is ___dubious about the claimed benefits of the new diet trend.