艰苦曲折 meaning in English

arduous and tortuous (way)

In the process of exploring truth , people will have to experience tremendous hardships and difficulties before they can come to understand the objective laws
在探求真理的过程中，人们对客观规律的认识要经过艰苦曲折的过程。
This paper discussed the material of equipmen t which was used to prepare diethyl oxalate by co coupling - regeneration reactio n wi th the method of weight . the seven kinds of metal material , such as 306 , 314l , 316l , zr , ti ( 2 ) , ti ( 10 ) , 1cr18ni9ti and one kind nonmetal material ( pe ) have been hung in the liquid compound in the regeneration reactor for 1500hours . the experiment ind icative that the corrosion rate of the 306 is the biggest , in the after is 316l , t i ( 10 ) , 1cr18ni9ti , zincorium ( zr ) , ti ( 2 ) , that of pe is lest ; 1cr18ni9ti is the better material of equipment
沙河市散装水泥事业起于上世纪九十年代初,经过十多年艰苦曲折的发展,目前我市水泥散装率达到20 %左右,这一水平还达不到河北省水泥平均散装水平,与先进省市"发散"水平相比更是相差太远.我们对发达国家和我国"发散"先进省市的考察和对比分析,可以看出除国家行政推动外,市场有效需求是拉动散装水泥发展的重要因素