#zhengqian-first{
    background: url("../images/product/zhengqian/1.jpg") top no-repeat;
}

#zhengqian-second{
    background: url("../images/product/zhengqian/2.jpg") top no-repeat;
}

#zhengqian-third{
    background: url("../images/product/zhengqian/3.jpg") top no-repeat;
}