改写：Filiz Ak et al 2014 have observed that when BAL troughs from lower ionization transitions are present the C iv troughs tend to be stronger and wider which means that C iv troughs might suffer from

According to Filiz Ak et al. (2014), the presence of BAL troughs from lower ionization transitions leads to stronger and wider C iv troughs. This suggests that the saturation of C iv troughs may be greater in the presence of BAL troughs from lower ionization transitions, as illustrated in Figure 5 of Filiz Ak et al. (2014).