请将这段中文翻译成英文并用学术语言和词语进行润色双重差分模型进行有效估计的前提是平行趋势假设成立因此要比较政策冲击之前实验组和对照组的时间趋势是否满足一致性。在本文设定的双重差分模型中主要关注的是在土十条政策实施之前资源型城市和非资源型城市的估计参数对应的平行时间趋势是否保持一致。表2的平行趋势检验结果显示在土十条政策实施之前解释变量的估计系数不显著并且处在0的附近这说明了在政策实施前实验组和对照

The prerequisite for effectively estimating the double difference model is that the parallel trends assumption holds, which requires comparing whether the time trends of the experimental and control groups before policy shocks are consistent. In the double difference model set in this paper, the focus is mainly on whether the estimated parallel time trends of resource-based cities and non-resource-based cities before the implementation of the "Ten Articles on Soil" policy remain consistent. The results of the parallel trend test in Table 2 show that before the implementation of the "Ten Articles on Soil" policy, the estimated coefficients of explanatory variables are not significant and close to zero, indicating that the time trends of the experimental and control groups are consistent, satisfying the parallel trend assumption of the difference model. After the implementation of the "Ten Articles on Soil" policy, the change trend of the estimated coefficients increases significantly, but the effect is not persistent, indicating that the policy has a significant promotion effect on the construction of urban green spaces (UGS) in resource-based cities, but the lack of timely adjustment of supporting policies based on the implementation of the policy has led to unclear economic governance responsibilities and inadequate governance funds. In the future, local governments should timely follow up on the implementation of policies, and make real-time adjustments and revisions to their plans according to specific circumstances