①扬长____(A.cháng B.zhǎng)而去
②枝折____(A.shé B.zhé)花落
③供____(A.gōng B.gòng)养不周
④不胜____(A.shēng B.shèng)其烦
⑤号____(A.háo B.hào)啕大哭
⑥引吭____(A.háng B.kéng)大叫
⑦战车千乘____(A.chéng B.shèng)
⑧一模____(A.mó B.mú)一样
如图,AB=AC,BD=DC,DE⊥AB,DF⊥AC,垂足分别是E,F.求证:DE=DF.