单项选择题
A.32.2;33.5 B.31.1;34.1 C.31.1;32.1 D.31.1;33.5
A.m0/(9i) B.m0/(8i) C.m0/(11i) D.m0/(4i)
A.4.357cm(→) B.4.357cm(←) C.2.643cm(→) D.2.643cm(←)