— Did you scold him for his mistake?— Yes, but it.A. I’d rather not doB. I’d better not

— Did you scold him for his mistake?
— Yes, but it.A. I’d rather not doB. I’d better not doC. I’d rather not have doneD. I’d better have not done

would rather接完成式表示对已发生的事情感到自责，具有虚拟的语气，其否定式在rather后加not。

这下我知道了