It was really _____ of your brother not to play the guitar while you were preparing your lessons.

However，at　times　this　balance　in　nature　is＿＿，resulting　in　anumber　of　possibly　unforeseen　effects．

 — Can Li Ping help me with my English?— I regret to tell you her English is ____ yours.

He thought himself to his friends because his family was rich.

Studies show that office workers are more ______to suffer from backache because they always sit before computer screens for long hours.