单项选择题
A.1/5 B.1/4 C.1/2 D.1/3
A.桩径800mm,桩长10m; B.桩径420mm,桩长2.5m; C.桩径1000mm,桩长4.5m; D.桩径600mm,桩长6m。
A.Ⅰ B.Ⅱ C.Ⅲ D.Ⅳ