His suddenly look of fear made it clear that he had something to do with the ma

他突然呈现的害怕的表情很清楚的表明他与此事有关 (ma 应该是MATTER)
it 是形式宾语,代表 that he had something to do with the matter

他忽然呈现出的害怕的表情很明显的说明他和ma（？）有关系

他突然期待的恐惧明确表示，他已经跟了马