紫甘蓝俗称紫包菜，叶片紫红，喜光照，含有丰富的维生素C和铁、硫等元素，成为人们餐桌上的美味佳肴，下列叙述正确的是（　　）

根据短文内容及首字母提示，填写所缺单词，使短文意思完整，每空只填一词。
    Millions of American children attend summer camp. Traditional American summer camps offer young people a c____  to play many sports. These camps may be in the mountains. Or they may be in the woods, or at a lake. O____   camps teach activities like painting or music. Or t____ teach computer programming or foreign languages. Children at all kinds of camps m____  new friends. They learn new skills and develop independence (独立).
    Some children go to camp d____  the day and return home at night. These places are c____  day camps. Children as y____  as four years old attend day camps. Others stay at camp all day and all night. Most children w____  attend overnight camp are between the ages of about six and sixteen.
    Children s____  at an overnight camp for between one and eight weeks. P____  can pay less than one-hundred dollars a week for an overnight camp. Or they can pay more than seven-hundred dollars a week.

我国社会主义经济制度的基础是（    ）