“我们现在看到的在2008年前是不常见的，”财政科学研究所研究员付志华说。

"What we're seeing was not very common before 2008," said Fu Zhihua, a research fellow at the research Institute for Fiscal Science.

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浙江大学高分子研究所，硅材料国家重点实验室曹健，孙景志，洪剑，杨新国，陈红征，汪茫。

Institute of Polymer Science and Engineering, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, People's Republic of China.

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