f'(x)
f(x) is a girl group from South Korea. They’re all pretty, but Sulli left because she got tired of being in the background and wanted to be the star.
My little sister says f(x) is the best group ever. I said, 'They’re good, but they’re not perfect.'
I told my friend f(x) is like a group of girls who are all pretty but sometimes argue about who gets the spotlight.
f(x) is like a group that’s got it all, but Sulli left because she wanted to be in the lead.