Young people tend to spend most of their out-of-school hours (1) ... with homework and other school commitments. These (2) ... them so busy that they have no time to (3) ... for other major projects. But there are some remarkable exceptions to this (4) ... . Some use any free time they have to (5) ... themselves to environmental issues. Ava Lang, for example, is only 14 but at: weekends she goes round restaurants to persuade the owners to (6) ... her with their used cooking oil. She then arranges for this to be (7) ... into biodiesel. Another youngster who does a considerable (8) ... of work to help others is Tim Fried. He races go-karts as a (9) ... of raising money for charitable causes. In this way he manages to (10) ... his love of sport with some socially useful work.