他们非常怀疑他的动机。

They’re very ___skeptical of his motives.

他对聘请顾问持怀疑态度。

He was ___skeptical about hiring a consultant.

就个人而言，我非常怀疑这个社会解决无家可归问题的能力。

Personally, I am very ___skeptical about this society's capacity to solve the homeless problem.