EXTRACT函数是选择一组值的非常高效的方法，但是如果预期的结果集只是单一对象，那么最好使用前面介绍的choose函数。
The EXTRACT function is a very efficient way to select a group of values, but if the expected result set is just a single object then you are better off using the CHOOSE function previously discussed.
那些哗众取宠的人(如声称能够使用单一治疗治愈许多无关疾病的人)，或者attact常规治疗的人，可能只是个庸医，最好不要相信他。
Anyone who makes sensational claims (such as being able to cure many unrelated diseases with a single therapy), or who attacks conventional treatment, is probably a quack and best avoided.
它只是作为一个单一的连接点来使用，以便向应用程序提供统一的或单一的数据库镜像。
It will simply serve as a single connection point to deliver the unified or single database image to the application.
用于换页定界的页的逻辑大体上相同，只是稍稍简单一些，因为不需要行计数器：使用getc库函数逐个读取字符。
The logic used for form-feed-delimited pages is roughly the same, but slightly simpler, as there is no need for a line counter: Read char by char using the getc library function.
这里提供的值比较复杂，但TODOItems的使用实际与单一值注释类型相符，只是这里的单一值是数组而已。
The value supplied here is fairly complex, but the use of TODOItems actually matches the single-value annotation style — except that the single value is an array.
这里提供的值比较复杂，但TODOItems的使用实际与单一值注释类型相符，只是这里的单一值是数组而已。
The value supplied here is fairly complex, but the use of TODOItems actually matches the single-value annotation style — except that the single value is an array.
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