甲烷与空气混合，爆炸极限为( )。
A．4.9%～15%
B．3%～15%
C．2.1%～9.5%
D．1.5%～8.5%
参考答案：A
We should think carefully about ________ Mr. Needham said at the meeting.
A．that
B．what
C．which
D．X
根据网络拓扑和R1的配置，解释并完成路由器R3的部分配置。 … R3(config)#crypto isakmp key (7) address (8) R3 (config)# crypto transform-set testvpn ah-md5-hmac esp-dex esp-md5-hmac (9) R3 (cfg-crypto-trans)#exit R3 (Config)#crypto map test 20 ipsec-isakmp R3 (config-crypto-map)#set peer 192.168.1.1 R3 (config-crypto-map)#set transform-set (10) …
