be efficacious

See: prevail
References in classic literature ?
All seem wise, and I do not suffer myself to doubt that any one of them would be efficacious.
Accordingly, under presence of seeking food, and such simples as might be efficacious in his malady, they deserted him and hastened forward upon the trail.
65g of xylitol per serving is considered to be efficacious in caries prevention.
It is clear that tightening up on enforcement would be efficacious in detecting and deterring future offenses.