In the early 1970s, for reasons that are still ill-understood, productivity growth slowed sharply, pulling down the trend rate of growth.
在70年代早期，因为一些至今仍无法明确的原因，生产率增长大幅下降，使得趋势增长率也随之下降。
2
So if increasing stroke rate isn't the answer, what about pulling harder and bulldozing through the water?
因此如果增加，敲打率不是答案，怎么样更努力拉并且通过水推平吗？
3
Not only is the feed rate established in the feed throat, but over-cooling the feed throat can extract as much as 20% of the total drive power by pulling heat constantly from zone 1.