Were it not for your help,I wound never be a good teacher.“要不是你的帮助”,应该指的是与过去事实相反,为何从句使用的是与现在事实相反的句型?

问题描述:

Were it not for your help,I wound never be a good teacher.
“要不是你的帮助”,应该指的是与过去事实相反,为何从句使用的是与现在事实相反的句型?