A.20% B.25% C.33% D.37% E.40%
A.3%~5% B.7%~9% C.10%~13% D.15%~20% E.25%~30%
A.正確 B.不正確,樣本代表性不夠 C.不正確,缺少對(duì)照組 D.不正確,年齡未標(biāo)化 E.不正確,沒有考慮分母