Which two options can be used as traffic descriptors when classifying and marking traffic？ （） ["incoming interface","Layer 2 differentiated services code point （DSCP）","Layer 3 IP precedence","outgoing interface"]
商业上称为桂榴石的宝石是（） ["铁钙铝榴石","镁铝榴石","锰铝榴石","钙铁榴石"]
皮带输送机的皮带连接一般采用粘接，请回答什么叫粘接？
按幼儿园教育活动的学科性质，可以将幼儿园教育活动分成哪几类活动？
从（）开始，尚书成为了一个庞大的机构。 ["西汉","三国","唐代","东汉"]
简述样品分析前处理的意义，主要方法有哪些？
