A.300/350×100/100=85.71% B.200/450×100/100=44.44% C.450/500×100/100=90% D.200/500×100/100=40% E.300/500×100/100=60%
A.100/300=0.33 B.100/400=0.25 C.100/150=0.67 D.50/400=0.125 E.350/400=0.87
A.橫斷面研究 B.實(shí)驗(yàn)研究 C.隊(duì)列研究 D.臨床研究 E.病例對照研究