Babysitters are big helpers. 保姆是很有用的助手。

　　They care for a child when parents are not at home. 当父母不在家时，保姆照顾他们的孩子。

　　Babysitters are very common in the United States. 保姆在美国很普遍。

　　How come? 这是为什么呢

　　According to US law, children under age 12 cannot stay alone in the house,  根据美国的法律，12岁以下的儿童是不能单独待在房子里的，

　　so a babysitter must be with a child if the parents are not at home. 所以父母不在家时，必须由保姆陪着孩子。

　　Then a child's parent pays money to the babysitter. 然后孩子的父母付钱给保姆。