【高中英语】Mary didn't answer my question immediately,but was los

【高中英语】Mary didn't answer my question immediately,but was lost in thought ,with her
Mary didn't answer my question immediately,but was lost in thought ,with her eyes____on the opposite wall
A.fixed B to fix C.fix D be fixing
为什么选A呢,with her eyes____on the opposite wall应该是她的眼睛盯着墙吧,过去分词不是表被动吗?