单项选择题
【单选题】设x、y轴为某平面图形的一对形心主轴,则下列结论正确的是( )。
单项选择题 假设当你发现所住的楼房起火时,你已被火势围困,最恰当的处理方式是()
单项选择题 To make things simpler and focus attention on what really matters, economists would
单项选择题 Rate-limiting enzyme in the synthesis of ketone bodies is