A.選取正橫附近物標(biāo)進(jìn)行觀測 B.選取首尾線附近物標(biāo)進(jìn)行觀測 C.選取較近物標(biāo)進(jìn)行觀測 D.選取孤立物標(biāo)進(jìn)行觀測
A.7nmile B.12nmile C.14nmile D.28nmile
A.7.8nmile B.8.7nmile C.7nmile D.8nmile