《灵枢·营卫生会》中“人生有两死，而无两生”之“两”是指
A．气血两虚B．表里两感C．营卫两衰D．精气两夺E．血汗两夺
参考答案：E
A ______ system placed between the company network and the outside world may limit outside access to the internal network.
A．firewall
B．modem
C．gateway
D．key
黄河“地上河”位于（ ）
A．上游
B．中游
C．下游
D．青藏高原
