【多选题】下列各项中,属于计算机操作系统的有( )。
【单选题】This memorial was built _______ those heroes who laid down their lives for the liberation of the poor people. [ ]
【判断题】行政复议决定书需要经当事人确认签字后生效。 2
【单选题】It was Alexander of _________who built the first ever world empire, covering North Africa, Mesopotamia, and Asia Minor.