应该选A should go 这儿是情态动词加动词原形,意思为:应该去C should have to中的have to 表示不得不去,在这'儿讲不通.这个句子中并没有虚拟语气的选项,,如果要用虚拟语气,就应该是: should have been, 表示"本来应该去,但没有去".如:I should have won the game. 我本来应该赢这场比赛的(言下之意就是:事实上没有赢.)不能选B的原因是,正确形式是: should have been中的been不能省略.
选A.应为You didn't go to see your uncle yesterday?---No,but I think I ______. 中的You didn't go to see your uncle yesterday?是与现在事实相反的.虚拟条件句是动词过去式.主语用should/would/could/might+动词原形．
