In the following essay, each blank has four choices. Choose the most suitable one from the four choices and write down in the answer sheet. There are two types of key technology: private key and public key. Private - key encryption methods are called (66) ciphers, information is encrypted with (67) both the sender and receiver hold privately. Public - key encryption methods are called (68) ciphers, (69) created for each user, encryption key and decryption key ale (70) .

A．two related keys ale

B．a key is

C．two unrelated keys ale

D．three keys ale

“朴雪”乳酸亚铁口服液可以有效地治疗人类缺铁性贫血症，这是因为其中的Fe²⁺进入人体后能（）

A.调节血液的酸碱平衡

B.构成红细胞中的血红蛋白

C.调节血液的渗透压

D.促使更多红细胞的产生