下列属于法定公益金用途的是（）。 ["弥补亏损","转增资本","报销职工医药费","改善职工集体福利设施支出"]
行辈
按照优先股票能否转换成其他品种，可分为（）。 ["不可赎回优先股票","可转换优先股票","可赎回优先股票","不可转换优先股票"]
教育实验研究
What should you do to reduce spanning-tree protocol BPDU traffic during extended periods ofinstability in your VLANs？（） ["Combine all the VLAN spanning trees into a single spanning tree","Set forward delay and max-age timers to the maximum possible values","None of the choices","Change the router VTP server mode","Disable the root bridge"]
简述双水相萃取和超临界萃取的概念与特点。
