用孕激素治疗闭经出现撤药性 * * 出血,表示()
A.子宫内膜萎缩
B.子宫内膜结核
C.子宫内膜对雌激素不起反应
D.子宫内膜已受雌激素影响
E.以上都不是
参考答案:D
It rained heavily this morning, but of my classmates were away from school.[ ]
A. neither
B. none
C. all
D. both
物料衡算通常采用哪几种基准?