1、Prescriptive grammar tells us how we should speak and write.
规定性语法告诉我们应该如何说和写。

2、This medication is only available with a prescriptive from a doctor.
这种药物只能通过医生的处方购买。

3、Some people criticize prescriptive approaches to language, arguing for more flexibility and acceptance of variation.
有些人批评规定性的语言处理方法，主张更灵活接纳变化。