Simplify the following text for a Grade 10 native English-speaking person.
Original: Only children below the age of 12 , senior citizens 65 years or older , or full-time Hong Kong students between the ages of 12 and 25 qualify for the concessionary rate .
Simplified: Only children below the age of 12 , senior citizens 65 years or older are eligible for the concessionary rate on all lines . Full-time Hong Kong students between the ages of 12 and 25 qualify for the concessionary rate on all lines except on Airport Express .