证书签名链依赖于()协议。
A.TCP
B.IP
C.IPSEC
D.X509
参考答案:D
—What are you going to be when you grow up, Sam?
—________ teacher like you. [ ]
A. A
B. An
C. The
D. /
腻子的主要作用是填补底漆后工件表面出现的细孔、裂缝、针眼等凹凸不平缺陷。