Childbirth preparation classes routinely teach pregnant women deep breathing exercises to minimize the pain and anxiety of labor.
分娩准备班,常例行公事地教孕妇们深呼吸的练习以减少分娩所带来的痛苦和忧郁。
This handbook covers the major classes of polymeric foams and discusses their chemistry, properties, preparation methods including commercial processes, and applications.
这本手册涵盖了聚合物泡沫的主要类别,并讨论它们的化学性质,制备方法,包括商业流程和应用程序。
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