is后为何有时接形容词有时接副词,例如he is good .he is well

这两个都是形容词.意义不同.good是好,well是健康.都是形容词.
adj.（形容词）
better,best
In a satisfactory condition; right or proper:
令人满意的；正确的或合适的：
All is well.
一切都尽如人意
Not ailing,infirm,or diseased; healthy.See Synonyms at healthy
健康的：没病的、非体弱的或没得病的；健康的参见 healthy
Cured or healed,as a wound.
康复的：康复的或治愈的,如伤口
Advisable; prudent:
贤明的；谨慎的：
It would be well not to ask.
最好不要问
Fortunate; good:
幸运的；好的：
It is well that you stayed.
你留下来很好
请及时采纳,多谢!