B 中的because of 绝对是个硬伤,because of表示逻辑上的原因,而by表示手段方式,二者意义不同,不能混用。比如: 1)Because of the storm, he didn't go there . (storm是原因) 2) He went there by train. (train是交通方式) 这个题里面,efficiency本身并不能刺激需求,它要通过价格杠杆来实现,这个价格就是方式,所以用by.
该题是GWD争议题。个人倾向选B。Although improved efficiency in converting harvested trees into wood products may reduce harvest rates, it will stimulate demand by increasing supply and lowering prices, thereby boosting consumption. 这里还是发生了分词修饰的逻辑错误。分词可以修饰逻辑主语it(这里it肯定指代improved efficiency,这点不用争论了),即提高的效率可以刺激消费量说的通,因为根据经济学原理,效率提高,生产量上升,单位成本下降,导致可能卖出价格下降,可能需求上升,可能消费的也多了;整句话即通过提高产量降低价格来刺激需求可以刺激消费也说的通,因为需求上升了,消费量自然也上升了;都说的通的话,即分词修饰逻辑表达不清(引自PREP破解版的解释)。所以A不正确。反观B,in converting harvested trees into wood products may reduce harvest rates, demand will be stimulated because of increasing supply and lowering prices, which boost; 根据谓语动词单复数判断,which就近修饰lowering prices逻辑表达正确。有人说不清楚是增加的供给boost消费还是降低的价格boost消费,根据经济学原理,价格显然更对。