This _____ my sister and those _____ my parents. [ ]

A. is; is

B. are; are

C. are; is

D. is; are

按钮，行程开关，万能转换开关按用途或控制对象分属于下列哪一类（）

A、低压保护电器

B、低压控制电器

C、低压主令电器

D、低压执行电器