It is important that we __ this message across to voters.

选A.原句是It is important that we should get this message across to voters.这里是虚拟语气的一个用法之一. 只不过should 可以省略的.怎么判断是虚拟语气呀这里是虚拟语气的一些特例。 表情绪.观点的形容词或名词也要用虚拟语气.如：necessary、important、impossible、natural、strange、surprising、funny、right、wrong、better、a pity ,the shame ,no wonder等。　　句型：It is.......that +主语从句，从句的谓语动词都要用 should+原型或 只用动词原型。　　eg:　　Do you think it is necessary that he (should)not be sent to Lingbao.　　It is strange that such a person should be our friend. 　一想要( desire ) 一宁愿( prefer ) 一坚持( insist )二命令( order , command ) 三建议( advise , suggest , propose/recommend) 四要求( demand , require , request , ask)中，无论主句谓语动词为何种时态，从句的谓语动词都用："should + do"。should可以省略。　　eg：He suggested that we (should) take the teacher's advice.　　He insisted that we (should) take the teacher's advice.　　He demand that we (should) take the teacher's advice.　　He ordered that we (should) take the teacher's advice. 虚拟语气还可用在定语从句中，表示：“早该做某事了”时，定语从句中的谓语动词须用虚拟语气，其虚拟语气的结构为：It is (high / about) time that + 主语+ 动词的过去式/ should + do（优先使用动词过去式） ，即从句用虚拟过去式。