A.1/180B.1/250C.1/300D.1/400
A.1/40B.1/50C.1/60D.1/70
A.強度;局部穩(wěn)定B.局部穩(wěn)定;剛度C.整體穩(wěn)定;強度D.整體穩(wěn)定;剛度