A.2 B.3 C.4 D.5
A.80%,且不宜小于70mm B.70%,且不宜小于70mm C.60%,且不宜小于70mm D.90%,且不宜小于70mm
A.扭轉(zhuǎn)效應(yīng) B.鞭端效應(yīng) C.共振 D.主體結(jié)構(gòu)破壞