第三节段如何译比较好？谢谢

There are four stages of addiction: 

1. Stage I, acute drug effects: Rewarding effects of drug result from neurobiologic changes in response to the acute drug use. Duration varies from hours to days.

2. Stage II, transformation to addiction: Associated with changes in neuronal function that accumulate with repeated administration and diminish over days or weeks after discontinuation of drug use. 

3. Stage III, relapse after extended periods of abstinence: Precipitated by an incubation of cue-induced craving (people, places, and things as triggers) and priming (relapse precipitated by drug exposure). 

4. Stage IV, end-stage addiction: Vulnerability to relapse endures for yr and results from prolonged changes at the cellular level.

上瘾有四个阶段:

1. 第一阶段，急性药物效应:由于药物急性使用导致的神经生物学变化而引起的药物奖赏效应，持续时间从小时到数天不等。

2. 第二阶段，成瘾:与神经功能的变化有关，这种变化随着反复用药而积累，在停药后几天或几周内逐渐减弱。

3. 第三阶段，长时间断药后的复发:由线索（人、地方和事物作为触发器）诱发的渴望的潜伏期和启动（暴露于药物后的复发）所加重。

4. 第四阶段，终末期成瘾:易持续复发，由细胞水平的长期变化引起。

•假性成瘾:因疼痛的治疗不足导致“寻求鸦片”行为（如“就诊”和多次急诊）。这些行为会随着疼痛的适当治疗而消失。

第三节段明白他的意思，如何译比较好？谢谢

yr是什么？year?you ?