质量认证是合格评定的主体活动，包括产品认证、（）、和实验室认可。
参考答案：质量管理体系认证
When he looked up, he suddenly found himself _____ by a group of teenagers, _____ looked at him
anxiously.[ ]
A. to be surrounded; which
B. surrounded; who
C. be surrounded; who
D. having been surrounded; which
某公司年初未分配利润为1000万元，盈余公积为500万元；本年实现净利润5000万元，分别提取法定盈余公积500万元、任意盈余公积250万元，宣告发放现金股利500万元。不考虑其他因素，该公司年末留存收益为（）万元。
A.5250
B.6000
C.6500
D.5750
