Over 1 billion people lack adequate housing. These people are found in every country of the world and, indeed, in almost every community. In some cases, they don't even have a roof over their heads. The problem is huge. Does this mean there is nothing that can be done? According to the people at Habitat(住处) for Humanity International(HFHI), there is plenty that can be done. HFHI was founded in 1976 by Millard and Linda Fuller, millionaires who decided their money could best be spent helping people. Since then, HFHI has helped fix and build homes for tens of thousands of people in the United States and over 30 other countries. HFHI believes that the homes should not be given as charity; instead, the organization follows a system known as partnership housing: The people who will live in the homes work together with volunteers on the construction and then gradually pay off the basic cost of the homes. These payments, together with contributions, enable HFHI to help other people. Throughout the world, the number of people who lack housing:【46】. HFHI stands for:【47】. The founders of HFHI: two【48】. The purpose of HFHI: help people【49】. The system by which HFHI offers help: through【50】.