The massive emission of greenhouse gases poses a serious threat to the ecological environment. In this context, the relevant effects of the carbon emission trading (CET) market, which promotes greenhouse gas emission reduction by market means, have been widely investigated. Taking the China's CET pilot as a research target, the heterogeneity and spillover effects of CET on green innovation are explored by using the sample data of 279 prefecture-level cities in China from 2008 to 2019. The results are as follows. First, on the whole, CET significantly promotes strategic green innovation, but it has no significant effect on substantive green innovation. Second, the green innovation effect of CET varies with the level of green innovation, and the heterogeneous effects of green innovation are also reflected in different degrees of marketization, fiscal decentralization and government environmental concern. Third, CET has a positive spillover effect on green innovation, and the spillover effect is more significant than the direct effect, accounting for 74.8% of the total effect. Finally, some corresponding policy suggestions are put forward according to the above research conclusions.

The commercial and financial attributes of oil have significantly changed the evolution characteristics of prices and returns of the international crude oil market. Using monthly data from April 2003 to October 2020, this paper identifies dynamic characteristics of oil’s commercial and financial attributes based on the structural vector autoregressive model (SVAR) and further analyzes their market effects with different attributes. The result shows that there are situations of commercial and financial attributes dominating, and dual attributes co-dominating for oil. Furthermore, their durations account for 51%, 23%, and 26% respectively, of the full sample. Besides, the reactions of crude oil price or return to the different properties of oil are heterogeneous. Specifically, the dual attributes of oil play the most important role in the price evolution of the international crude oil market, which is 80.851. There are significant differences among the impact of different attributes of oil on the evolution of international crude oil market returns, which are 0.009, −0.008, and −0.004, respectively. Then, some relevant recommendations for policy-makers and investors based on the above research conclusions are also put forward.