---Irangyouyesterdayafternoon.Amananswered,butIdidn’trecognizethevoice

---I rang you yesterday afternoon. A man answered, but I didn’t recognize the voice.--- Oh, it ____ my uncle. He was in my room thenA.must have beenB.should have beenC.must beD.should be

A解析考查情态动词表推测。因为是对过去事实表推测，要用情态动词加完成时态，排除C,D；should have been表本应该是实际不是；must have been肯定是；根据He was in my room then，可知是我叔叔的可能性很大。所以选A。

谢谢解答