求助：GWD-25-Q24（翘首期盼牛牛们的回答）

800120summer

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.

A.     in converting harvested trees into wood products may reduce harvest

 rates, it will stimulate demand by increasing supply and lowering prices,

thereby boosting.

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.

C.     Of converting harvested trees into wood products may reduce harvest

rates, it will stimulate demand by increasing supply and lowering prices,

which boosts.

D.     Of harvested trees being converted into wood products may reduce

harvest rates, it will stimulate demand, because it will increase supply

and lower prices, thereby boosting.

E.      When harvested trees are converted into wood products may reduce

harvest rates, demand will be stimulated because of increasing supply

and lowering prices, which boost.

答案是B，我觉得选A，我首先通过应该用boosting直接排除得B，不知道为何选B，希望牛牛能够给解答一下，万分感谢！

wwk_lion

首先应该排除A，因为boosting是错的。

boost是和stimulate对应的～

liverpool123

我觉得A的it用法不对，boosting应该可以的，现代分词短语作状语

相当于which will boost ,it这样用要指代一句话，但是明显不是，只是一个短语，所以这样我觉得有问题，不知道其他人怎么看？

800120summer

谢谢解答！

可是it为什么不能指代improved efficiency
            呢？

liverpool123

Although 是个从句，it如果用作主句主语的话，那么就是形式主语,它只能指代前面的一句话，但是it指代从句一句话，好像不能这样用，那时候用which，as会更好，属于

非限制性定语从句。

我的理解也是片面的吧，我7年左右没有学习过语法了。

如果句子改为下面这样，it就可以指代Improved efficiency了

Improved efficiency in converting harvested trees into wood products

may reduce harvest rates, But it will stimulate demand by increasing supply and

lowering prices, thereby boosting consumption.

800120summer

谢谢楼上的牛牛们，完全明白了！