测定外源化学物LD50（LC50），通常要求计算实验动物接触化合物之后多长时间内的总
题型：单项选择题 A1型题
问题：
测定外源化学物LD50（LC50），通常要求计算实验动物接触化合物之后多长时间内的总死亡数（）
A.2天
B.4天
C.7天
D.14天
E.30天
题型：单项选择题 A1型题
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