You can pay to be upgraded to a business class seat.你可以付费升级到商务舱。Helicopters have been upgraded and modernized.直升机已经更新换代，装配了现代化设备。They upgraded the land by improving it with new buildings.他们建造新楼房来提高土地的等级....
In the worst - case scenario, UV light mutates DNA, leading to premature aging or skin cancer.在最差的情况下, 紫外线能使DNA发生突变, 于是导致提前老化或皮肤癌.In this paper , UV - Vis spectra of oil, oil, sunflower oil and hogwash oil were studied.研...