LET/ALLOWsomething that is impermissible cannot be allowed 不许可的，不允许的OPP permissible
Examples from the Corpus
impermissible• The conduct of the officers in this case was impermissible.• I consider that such doctrine would be dangerous and impermissible.• To switch off the respirator otherwise is impermissible.• Codes of conduct were beginning to emerge and a range of permissible and impermissible subjects was being informally drawn up.