佣书
参考答案：
中国古代受人雇佣以抄书为业的人。
My best friend Lily is _________ with her mother and _________ her with housework.[ ]
A. stays; helps
B. staying helping
C. stay, help
D. staying, helps
变频器频率给定有两种方法，一种是用变频器的操作面板来输入频率的数字量；另一种是（）
