有种担忧是NASA可能丢失其数十年运行航天器的专业知识和经验，而商业公司在学习过程中却步履蹒跚。

A worry is also that the decades of expertise and experience within NASA in operating spacecraft will be lost, and that the commercial companies might stumble as they learn.

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摘要：材料进步是我们技术进步的重要因素，然而，材料的发现和开发过程却步履蹒跚。

Abstract: Advances in materials are an important contributor to our technological progress, and yet the process of materials discovery and development itself is slow.

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