下列哪项不是艾滋病对人群危害的表现（）。
A.感染的普遍性
B.威胁的长期性
C.控制和治疗的困难性
D.资源的消耗性
E.社会的毁灭性
参考答案：A
正常条件下作为脑组织惟一能量来源的物质是（）
A.糖
B.氨基酸
C.甘油
D.蛋白质
E.酮体
—I don't know why Denise started crying when I mentioned the wedding.
—It ______ what you said about her brother. Or, perhaps she is just nervous. [ ]
A. should have been
B. couldn't have been
C. could have been
D. must have been
