The boy was frail and never ganged with his fellows at school.

这个男孩身虚弱, 从不和同学们一起玩。

His frail hands could hardly hold a cup.

他虚弱手连杯子也拿不住。

He is frail after his illness.

他生病后很虚弱。

Physically he is frail and must sustain himself by imbibing magical potions of his own creation.

他天生身虚弱，必须服用他自己创造魔法药剂来维持自己生命。