最令航天业担忧的是钇供应紧张。钇是高温防护涂层中的关键成分，可防止发动机和涡轮在高温下“熔化”，一旦无法定期施涂相关涂层，发动机便无法正常服役。
第三十八条 纳税人发生应税交易，开具增值税专用发票后，发生开票有误或者销售折让、中止、退回等情形的，应当按照国务院税务主管部门的规定进行作废处理或者开具红字增值税专用发票；未按规定进行作废处理或者开具红字增值税专用发票的，不得依照本条例第十三条和第十四条的规定扣减销项税额或者销售额。
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Now, genetic evidence has revealed a striking imbalance in these prehistoric trysts, suggesting that interbreeding was mostly between male Neanderthals and female humans.