VAR模型 英文表述问题

请问各位前辈，如何比较专业地用 英语表述一下句子：
1. 滞后1、2、5期的股指波动率变动对当期股指波动率存在显著的正向作用

2.滞后3期的股指波动率对当期股指波动率不存在显著作用。

3.滞后2期与5期的GDP上升，对FDI分别存在0.001820与0.001692的动量使得当期FDI减小

1. The changes of the stock index volatility lagging 1,2 or 5 periods has a significant positive effect on the current stock index volatility.

2. The stock index volatility lagging three periods does not have a significant effect on the current stock index volatility.

3. With the increase of the GDP lagging 2 or 5 periods, there respectively exists the momentum of 0.001820 and 0.001692 for FDI, reducing the FDI in the current period.