【单选题】交流伺服系统的主要分为:开环伺服系统、半闭环伺服系统和( )。
【单选题】Those students don't have to be made ______. They are all diligent students.
【单选题】This school doesn't have ______ it did ten years ago. [ ]
D.
so many as students as
【简答题】2018年我国原油进口依存度 %,天然气为45.3%,铀进口依存度已达90%。
【单选题】In those days, few people liked taking a bus, _____? [ ]