He came here without friends or ______and made his fortune. A. possessions B. possession C. wealths D. good 答案:A
如图,观察下列图形,寻找对顶角.
(1)观察图(1),图中共有几对对顶角?
(2)观察图(2),图中共有几对对顶角?
(3)观察图(3),图中共有几对对顶角?
(4)研究(1)~(3)小题中直线的条数与对顶角的对数之间的关系,若有2 005条直线相交于一点,则可以形成多少对对顶角?