1 sentence for 一線 (yī​xiàn — front line)

1. 即使在一线城市，人们也必须购买“学区”公寓才能进入好学校。

   jí​shǐ zài yī​xiàn chéng​shì, rén​men yě bì​xū gòu​mǎi“ xué​qū” gōng​yù cái​néng jìn​rù hǎo xué​xiào.

   Even in the first tier cities, people have to buy “School-District” apartments in order to enter good schools.

   Source: CCMatrix