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。
Point lookups are useful, but the operation you'll reach for more often is a range query: give the tree a rectangular region and retrieve every point inside it, without scanning the entire dataset.
，这一点在搜狗输入法2026中也有详细论述
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