有时候，用户可能希望只根据一个可用的选择条件对数据排序，而将其他条件留空，或者不选择任何条件，将所有条件留空。

Sometimes the user may want to sort the data only on one of the available selection criteria and leave the others blank or select no criteria to sort the data by leaving all the criteria blank.

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他们发现，如果人们有条件在家工作，压缩工作时间，那么他们就可以选择更为健康的生活方式，锻炼身体的机会增多。睡眠也会更好。

They found that if people have the ability to work from home and to compress work weeks, they are more likely to make healthier lifestyle choices, to exercise more and to sleep better.

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图6.42。选择函数，用于有条件地选择两个可能的输出。

Figure 6.42. The Select function used to conditionally switch between two possible outputs.

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