有许多不同类型的认证机制，而每一种类型都难以尽善尽美。

There are many diverse types of authentication mechanism, and each is difficult to get right.

youdao

有许多不同类型的认证机制，而每一种类型都难以尽善尽美。

There are many diverse types of authentication mechanism, and each is difficult to get right.

youdao