单项选择题
A.1:10000 B.1:5000 C.1:2000 D.1:500
A.M=0,FQ≠0,FN≠0 B.M≠0,FQ=0,FN≠0 C.M=0,FQ=0,FN≠0 D.M≠0,FQ≠0,FN≠0
A.实心的混凝土预制桩 B.下端封闭的管桩 C.沉管灌注桩 D.钻孔桩