物流系统的本质在理论上可以用时间维和空间维的物态变化来揭示。
参考答案：对
I have been living in the United States for twenty years, but seldom _____ so lonely as now．
A．have I felt
B．I had felt
C．I have felt
D．had I felt
对于绝经后乳腺癌患者，内分泌治疗首选的物药（）
A.芳香化酶抑制剂
B.雌激素
C.三苯氧胺+氟尿嘧啶
D.赫赛汀
E.紫杉醇
