题目

    Child models are very much in demand all across the world. Many magazines and online stores that sell products for children like their models young.For this reason,they seek out children who can model clothing and have no problem posing（摆姿势）and smiling for the camera．Those who are seeking out child models for thelr advertising can go to online modeling sites and view plotures of children who are web models．They can take a look at their portfolio（整套照片）and decide whether they will accept them．     Parents who are seeking to get their children into the modeli__________________________叫做逆定理。