问题
单项选择题
Only when total production expands faster than the rate of labor force growth plus the rate of productivity increase and minus the rate with average annual hours fall so does the unemployment rate.
A. at which average annual hours fall does the umemployment rate fall.
B. which average annual hours fall so does the umemployment rate.
C. in which average annual hours fall and so does the umemployment.
D. which average annual hours fall does the umemployment rate fall.
答案
参考答案：A
解析：第七句的问题有两个：一是at which的用法，二是以only、never等副词开始的主句动词的倒装。此句中的which指之前的rate，因此应该使用介词at。主句之前的状语是由only when开始的，所以全句应该以Only when... does... do的形式出现。