12. After gradual declension down to about 39 hours in 1970, the workweek in the United States has steadily increased to the point that the average worker now puts in an estimated 164 extra hours of paid labor a year.

(A)            After gradual declension down

(B)           Following a gradual declension down

(C)           After gradual declining down

(D)           After gradually declining

(E)           Following gradually declining

答案是D，但我不明白E为什么错？期待NN的讲解

这句话是讲工作时间先减后增的话题，句子的主语是 the workweek, 前面的短语是修饰主语的。前半句意思说，工作时间在1970年之前是不断下降的，而1970年是最低点，后面句子说工作时间渐渐变长。after，可以有转折的意思，但是follow则是一个延续的意思。所以用follow是不符合句子的语境的。