Her looks reflected the thoughts passing through her mind.

此句结构分析：
Her looks为此句主语,reflected是谓语动词,the thoughts,是宾语,passing through her mind,是现在分词做非谓语动词修饰thoughts.因为thoughts与pass through是主动关系,所以用现在分词.（如果是被动则用过去分词形式）
此句意思为：她的表情反映出了她脑子里的想法.
her looks是她的表情的意思.
pass through是一个词组,译为：通过,穿过之意.此句中是指通过它脑子中的想法,意译为：她的想法.