某药的半衰期为12小时,给药1克后血浆的最高浓度为4mg%,如果每12小时用药1克,多少时间后可达到10mg%
A. 1天
B. 3天
C. 6天
D. 12小时
E. 不可能
set1 = {1,2,3} set2 = {2,3,4} set1和set2的并集是?
A. {1,2,3}
B. {2,3,4}
C. {1,2,3,4}
D. {2,3}
set1 = {1,2,3} set2 = {2,3,4} set1和set2的交集是?
A. {1,2,3}
B. {2,3,4}
C. {1,2,3,4}
D. {2,3}
set1 = {1,2,3} set2 = {2,3,4} set1和set2的差集是?
A. {1}
B. {1,}
C. {1,2,3,4}
D. {1,2,3}