A. B. C. D.
A.任意荷載可分解為對(duì)稱(chēng)荷載和反對(duì)稱(chēng)荷載 B.選取對(duì)稱(chēng)的基本體系,取對(duì)稱(chēng)力和反對(duì)稱(chēng)力作為基本未知量 C.對(duì)稱(chēng)荷載作用下,反對(duì)稱(chēng)未知力為零 D.反對(duì)稱(chēng)荷載作用下,對(duì)稱(chēng)未知力為零