The list of recommendations includes: (1) keeping the two existing indexes on the CUSTOMER table and (2) creating 1 index and keeping 1 index for the DISTRICT table.
建议包括：(1)保留CUSTOMER表上已有的两个索引，并且(2)创建一个索引，保留用于DISTRICT 表的一个索引。
But you cannot always be on the top level. Otherwise Ferrari and McLaren would win all the RACES with a 1-2, or 1-3, or a 1-4, and the first four places would be sold to Ferrari and McLaren.
但是你不可能一直处在巅峰水平，否则法拉利和迈凯轮将会赢得所有比赛的1 - 2名、1 - 3名或1 - 4名，头4名总归会是法拉利或和迈凯轮的。
But you cannot always be on the top level. Otherwise Ferrari and McLaren would win all the RACES with a 1-2, or 1-3, or a 1-4, and the first four places would be sold to Ferrari and McLaren.
但是你不可能一直处在巅峰水平，否则法拉利和迈凯轮将会赢得所有比赛的1 - 2名、1 - 3名或1 - 4名，头4名总归会是法拉利或和迈凯轮的。
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