边际替代率
参考答案:
指如果消费者在收到额外一单位商品X之后要保持满足水平不变而必须放弃的商品Y的数量。
—Wow. It is rather cold today. —Yes. ____ yesterday.
A. So it is B. So it was C. So was
用已知抗原阳性的切片作对照,与待检标本同时进行免疫细胞化学染色,对照片应呈阳性结果,称为()
A.阳性对照
B.阴性对照
C.空白对照
D.自身对照
E.阳断试验对照