I was about to leave when I suddenly hear someone above_____A to speakB speakingC being spokenD was spoken

填B.speaking
译文：我正准备离开的时候听到有人在上面说话.
1.hear someone speaking:听到某人在说话,现在分词表示伴随
2.感官动词（see,hear,feel 等）后面如果加不定式,需把不定式符号to省略,因此A to speak为误,当然,不定式表达的动作是还没有发生的动作,所有这里也不用.
C、D 的错误在于,someone（逻辑主语）和非谓语动词之间是主动的关系,另外D是谓语动词,更不对了,切记英语句子永远不能有两个谓语动词出现.