下列加横线字读音都符合拼写规则的一组是（    ）

缺词填空 根据短文内容及首字母提示补全单词
    UNICEF works all over the world.
    UNICEF helps make the world a better place for c____ . We provide clean water, enough food and e____ for poor children in many countries.
    We want children to be healthy so we try to p____  illness. When they're sick, we pay for them to go to a doctor.We also think it's i____  that children go to school. Many children in p____  countries have to work to earn m____  for their families so they can't go to school.
    UNICEF raises money by s____ Christmas cards and organizing other fund-raising a____ .
    There are many w____  you can help UNICEF. You can send a donation or do some v____  work.

北方地区与南方地区的分界线是　　　　　　　　　　　　　　　　　（　　）

若函数f（x）=﹣2x³+2tx²+1存在唯一的零点，则实数t的取值范围为____ 

下面为张汀的漫画《解放道路上的障碍》，登载于1947年的《东北画报》。这里的“障碍”主要是指（    ）