矿山瓦斯检测实际上是( )检测。
A.甲烷
B.乙炔
C.二氧化碳
D.硫化氢
参考答案:A
解析:瓦斯检测实际上是指甲烷检测,主要检测甲烷在空气中的体积浓度。
Certificates are (16) documents attesting to the (17) of a public key to an individual or other entity. They allow verification of the claim that a given public key does in fact belong to a given individual. Certificates help prevent someone from using a phony key to (18) someone else. In their simplest form, Certificates contain a public key and a name. As commonly used, a certificate also contains an (19) date, the name of the CA that issued the certificate, a serial number, and perhaps other information. Most importantly, it contains the digital (20) of the certificate issuer. The most widely accepted format for certificates is X.509, thus, Certificates can be read or written by any application complying with X.509.
A.signature
B.mark
C.stamp
D.hypertext
电力系统中电压的质量取决于系统中()功率的平衡,()功率不足,电压降低。