Before revision:  Many existing studies show the vulnerabilities of machine learning and deep learning modelsagainst adversarial examples . {\em   However, most existing works currently focus on evasion attack on text data instead of positioning attack , also named backdoor attack .
After revision:  Many existing studies show the vulnerabilities of machine learning and deep learning modelsagainst adversarial examples . {\em adversarial attacks, the poisoned models with malicious intentions are much more dangerous in real life. However, most existing works currently focus on evasion attack on text data instead of positioning attack , also named backdoor attack .