A.有計(jì)劃觀察和無計(jì)劃觀察 B.無計(jì)劃觀察 C.有計(jì)劃觀察 D.隨意觀察
A.25-30 B.31-36 C.13-18 D.19-24
A.19-24 B.31-36 C.25-30 D.13-18