长难句倒装结构４

Exercise

Only when total production expands faster than the rate of labor force growth plus the rate of productivity increase and minus the rate at which average annual hours fall does the unemployment rate fall.

In addition, difficult as it is to believe, there are desert fish which can survive through years of drought in the form of inactive eggs.

In reality, though, the BBC dictionary will be purchased by a far wider range of language learners, as will the other two dictionaries.

要点：这是一个倒装句。不倒装的话，应为：the unemployment fall only when ...hours fall. when引导的从句主干为: total production expands faster than the rate ... plus the rate ... and minus the rate...,最后一个rate又是由at which引导的从句修饰的。
译文：只有当总产量增长快于劳工数量加产量的增长，并减去平均工作小时时，失业率才会下降。

要点：在由as引导的让步状语从句中，句中的形容词或副词甚至动词根据强调的需要放在句首，而as置于其后。
译文：此外，让人难以置信的是，有一种生长在沙漠地区的水生动物在干旱时能以其非活性卵的形态存活多年。

要点：as承接前面从句之语，意为“如。。。一样”，并且要求主谓倒装。
译文：尽管如此，实际上购买英国BBC广播公司的字典的语言学习者的范围将会更大一些，其他两本字典也是这样.