IPsec是为了弥补（）协议簇的安全缺陷，为IP层及其上层协议提护而设计的。
A.HTTP
B.TCP/IP
C.SNMP
D.PPP
参考答案：B
--- John failed his final exam.
-- I’m not surprised at the news at all. _______, he is never seen busy with his lessons.
A．Above all
B．In all
C．First of all
D．After all
治疗肾气虚不孕症的代表方是（）。
A．养精种玉汤
B．毓麟珠
C．温胞饮
D．开郁种玉汤
