A.從發(fā)現(xiàn)無(wú)效時(shí)起無(wú)效 B.從法院判決無(wú)效時(shí)起無(wú)效 C.從仲裁機(jī)構(gòu)裁決無(wú)效時(shí)起無(wú)效 D.從訂立時(shí)起無(wú)效
A.要約 B.承諾 C.要約邀請(qǐng) D.要約通知