泵的保护器作用以及种类是什么？
Given： Which statement is true about the objects referenced by snoog， snooch， and booch immediately after line23 executes？（） ["None of these objects are eligible for garbage collection.","Only the object referenced by booch is eligible for garbage collection.","Only the object referenced by snoog is eligible for garbage collection.","Only the object referenced by snooch is eligible for garbage collection.","The objects referenced by snooch and booch are eligible for garbage collection."]
果菜类蔬菜在生长的中后期需要（）来减少营养消耗，改善通风透光。 ["束叶","灌水","摘叶","施肥"]
下列关于混凝土小型空心砌块砌体施工的说法，错误的是（）。 ["施工采用的小砌块的产品龄期不应小于28日","普通混凝土小型空心砌块砌体，宜提前1～2日浇水湿润","小砌块应将生产时的底面朝上反砌于墙上，小砌块墙体宜逐块坐（铺）浆砌筑","墙体临时间断处应砌成斜槎，斜槎水平投影长度不应小于斜槎高度"]
Click the Exhibit button. A customer has several interconnected core rings (see exhibit). They want to create several irtual rings?utilizing their OC-192 backbone (nodes 1,2,3,4). What should you recommend?（） [" PPMN with BLSR rings"," PPMN with UPSR rings"," 1:N protection on all core circuits"," multi-ring interconnect with BLSR ring"]
每一个XML文档必须有（），但（）的XML文档不一定是有效的。
