The way we cook is important．In many countries，the two choices are（61）___ （nature） gas or electric-powered stoves．

The World Health Organization warns that millions of people（62）___ （suffer） from indoor air pollution at present time，which results fuom the use of（63）___（danger） fuels and cook-stoves in the home．

WHO officials say nearly three billion people are （64）___ （able） to use clean fuels and technologies for cooking，heating and lighting．As a result，more than seven million people die from exposure to indoor or outdoor air pollution each year．Most of the deaths are in （65）___ （develop） countries，such as lndia，China and Latin American countries．

WHO officials say opening a window or door （66）___ （let）out the harmful air will not correct the situation （67）___ will only pollute the outdoors．

Nigel Bruce，（68）___ is a professor of Public Health at the University of Liverpool，says researchers are developing good cook-stoves and other equipment to burn fuels （69）___ a more efficient way．

But，this is just a start．It is urging developing countries to use（70）___ （clean） fuels and increase access to cleaner and more modern cooking and heating appliances（用具）．