beneficial
The definition for beneficial is "Helpful." Used in a sentence: there is no doubt that eating vegetables is beneficial to one's health.
combative
The definition for combative is "Eager to fight." Used in a sentence: The teacher suggested the combative student channel his aggression into boxing.
dubious
The definition for dubious is "Questionable." Used in a sentence: Karl found Kevin's claim that he was sick dubious, as he had just seen him playing football.
ethical
The definition for ethical is "Conforming to accepted standards." Used in a sentence: Mary did the ethical thing and turned in the diamond necklace she found.
supple
The definition for supple is "Flexible." Used in a sentence: The supple leather coat draped like soft cloth around her shoulders.