教师为本。
用人单位账户余额少于应当缴纳的社会保险费的，社会保险费征收机构可以要求该用人单位提供担保，签订延期缴费协议。
可燃气体浓度（）爆炸下限时，即不着火也不爆炸 ["高于","低于"]
摩擦学研究的理论和实践包括设计和计算、润滑材料和（）方法，摩擦材料和表面状态以及摩擦（）和预报等。
What does the term application partitioning refer to?（） ["The feature of a forms application enabling it to run both in client-server mode and on the Web. ","Storing PL\/SQL program units between the Oracle server and the application to make optimal use of available resources. ","The nature of a three-tier architecture, where the form module and processing software reside on an application server. ","The feature of a forms application that is able to use Ethernet, twisted pair, and wireless data connections."]
平衡式、部分平衡式和非平衡式机械密封有何区别？
