WASHINGTON (AP) — Biofuels made from the leftovers of harvested corn plants are worse than gasoline for global warming in the short term, a study shows, challenging the Obama administration's conclusions that they are a much cleaner oil alternative and will help combat climate change.

Leading automakers gathered in Beijing Sunday for China's biggest car show, expressing confidence in the world's largest car market even though lacklustre economic growth and environmental restrictions have generated uncertainty. Spectators and journalists crowded around displays at the Beijing International Automotive Exhibition, which features more than 1,100 vehicles and opens to the public on Monday, while female models drew the attention of photographers. General Motors, Toyota, Volkswagen and Hyundai are among the global manufacturers on the list of attendees, along with SAIC and Dongfeng, China's number one and two domestic automakers. "This is obviously an incredibly important market for General Motors," its president Dan Ammann told reporters, saying China since 2010 had been the US automaker's largest market which now accounted for a third of total volume.

DENVER (AP) — Once the province of activists and stoners, the traditional pot holiday of April 20 has gone mainstream in the first state in the nation to legalize recreational marijuana.