据《素问·生气通天论》，人体阴阳平衡的关键是（）
A.阳气固密于外
B.阴精充足
C.精神清静
D.阴气固守于内
E.传精神，服天气
参考答案：A
__ has been mentioned above, continued chairman after he took a sip of coffee, ____ the project must be carried out before spring flood comes.
A．As; that
B．That; which
C．This; which
D．It; that
水中含有大量铁则有（）
A．苦味
B．咸味
C．涩味
D．沼泽味
E．汽油味
