Priority seats

I sometimes see young students sit on priority seats on a bus. The other day a male and a female students were on the priority seats on a 99 route bus. When a mother and a baby on a pram got on the bus, the student holing ECU student card ignored her and didn't give his seat to her. At last an old man offered his seat to her. I was surprised. I think that young people except patients shouldn't keep priority seats. I experienced bad thing on a 34 route bus. A boy holding a skateboard got a priority seat, and I couldn't sit down on the bus. I've almost fell over! The sign of priority seat is big on the window!