请观原句：
None of these answers really explains why the century-long decline in working hours has <gone into reverse> in America but not elsewhere.
请问 reverse 此处作可数名词义，为何其前无 a呢？
go into reverse 是习语，意思是“出现逆转；转为对立面”，不用冠词。如：
In 2008 economic growth went into reverse. 2008年，经济增长发生了逆转。（摘自《牛津高阶英汉双解词典》第9 版p.1832）
