Eng: Rigorous...

嚴

Rigid, Rigorous, Serious, Severe, Stern, Strict, Tight

苛

Exacting, Harsh, Petty, Rigorous, Severe, Small

嚴謹

Rigorous

緊密

Close, Close-knit, Closely, Compact, Intense, Orderly, Precise, Rapid, Rigorous, Tightly