在先

I had collected material previous to writing.

我在写作以搜集了材料。

Sugar, oil and metals are refined before use.

糖, 油和金属在使用须提炼。

Filter out all the dirt before using the water.

在用水以其中不清洁的东西过滤掉。

The research tools are the vision-eikon-compare test 1 and test 2.

挑选受者在同一时段进卷，再进卷，完毕再进比较分析。