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.

许多选民仍然对这位政客的竞选承诺表示怀疑。

Many voters remain ___dubious about the politician's campaign promises.

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.