诱发性动物模型的优点()。
A.简单、方便
B.有些人类疾病不能用人工方法诱发动物疾病模型
C.其它因素容易控制
D.短时间复制大量的动物模型
参考答案:A, C, D
—David ,look at the man in white over there. Can you tell me ______?
—He is a doctor. [ ]
A. who is he
B. who he is
C. what is he
D. what he is
有甲乙两个同一有色物质不同浓度的溶液,在相同条件下测得吸光度分别为甲:0.30 乙:0.20若甲的含量为0.015%,则乙的含量为()
A.0.060%
B.0.010%
C.0.005%
D.0.040%