Define abbreviations that are not standard in this field in a footnote to be placed on the first page of the article.
要在这篇文章第一页的脚注里定义一下用在本文中的在这个领域里不标准的缩写词.
这是个祈使句：
Define 是谓语动词
abbreviations宾语
that are not standard in this field是abbreviations的定语
in a footnote to be placed on the first page of the article.整个介词短语作谓语动词的地点状语
在这个介词短语中to be placed不定式作后置定语,on the first page of the article介词短语作后置定语,都用来修饰a footnote.