He demand for paints(主语）//has been(系动词) //so heavy (表语)this month //(结果状语）that our stocks, generally quite high at this time of the year, have fallen to a minimum.

参考译文：他这个月对油漆的需求如此之大，以至于我们的库存，在每年的这个时候都相当高，已经降到了最低水平。

one's demand for sth某人对物的需求

上面的句子应该为下面句子

His demand for paints has been so heavy this month that our stocks, generally quite high at this time of the year, have fallen to a minimum.

generally quite high at this time of the year相当于非限制性定语从句“which is generally quite high at this time of the year”which指代“stock”