1·The actual task of building back this critical infrastructure is a challenge of unprecedented proportions.
重建这些急需的基础设施的实际任务是一个史无前例的挑战。
2·The prevalence of childhood overweight and obesity is reaching unprecedented proportions in Australia and internationally.
在澳大利亚和国际上，儿童超重和肥胖的患病率达到了前所未有的比例。