Some photos taken by the children.为什么没有were?定语指句子哪一部分?什么叫过去分

Some photos taken by the children.为什么没有were?定语指句子哪一部分?什么叫过去分 some photos taken by the children of Yushu Qinghai 为什么用taken 我在做英语题时有这样一个句子：Some photos taken by children. The photos _ were taken by our headmaster.kkkkkkkkkkkkkkkkkk The photos _ were taken by our headmaster.快 The photos _ were taken by our headmaster. Some photes taken by African children.为什么不是was taken some children is taken good care by the nurse为什么用is the photos were taken（ in 1998） 对划线部分提问 Some photos____by African children.A.are taken B.were taken the pictures which were taken by me中的which were taken可以用什么换 What are on show in the museum?Some photos——by the children