单选题All possible means  

问题补充：

单选题Allpossiblemeanstosavethewoundedsoldier.A.has been triedB.have been triedC.is to be triedD.are trying

答案：

B解析means是单复数同形名词，谓语的单复数取决于句子意思，如all/those/a lot of means动词用复数；every/this/that means动词用单数。