An army spokesman stressed that all the soldiers had been ordered ________ clear warnings before firing any shots．
A.to issueB.being issuedC.to have issuedD.to be issued在线课程A
解析：
本题考查不定式作主语补足语的用法及非谓语动词的时态和语态。order sb．to do sth．命令某人做某事句中的order是以被动形式出现的，故其后应接不定式作主语补足语。又因issue（发布）的宾语是clear warnings，且该动作尚未发生，故选不定式的一般式作主补。