问题描述：
问个英语语法问题
In 2009,basic and applied research spending constituted 4.7% and 12.6% of total R&D expenditure,dropping from 2000 levels of 5.2% and 17%,respectively.
这里的dropping作什么成分啊?
In 2009,basic and applied research spending constituted 4.7% and 12.6% of total R&D expenditure,dropping from 2000 levels of 5.2% and 17%,respectively.
这里的dropping作什么成分啊?
问题解答：
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