对于一个初始序列 [5, 2, 8, 1, 9]，使用冒泡排序进行第一趟排序后，序列的状态是什么？

Which phrase correctly completes this academic sentence: '______ early Mayan communities developed complex irrigation systems.'

In a situation where someone is advised to make the best of their life, which of the following phrases would be appropriate to use instead of describing a fire as a 'terrible tragedy'?

在神经语言程序学（NLP）中，以下哪项最准确地描述了'锚定'的概念？

函数f(x)在点x=a处的导数存在，意味着函数在这一点上的图形有一个明确的切线。