单项选择题
A.小于10% B.小于或等于10% C.大于10% D.等于10%
A.波纹或筋底部 B.试件上任意点 C.事先确定的位置 D.波纹或筋顶部
A.10s,15s B.5s,10s C.10s,20s D.10s,30s