In the last eight years, a lot of bees have disappeared. Scientists have been studying why those bees have been leaving their hives and not returning. They believe that their living environment may be changing. Now, the US government is stepping in to help fight this problem. President Barack Obama has asked for $50 million(310 million yuan ) in his 2015 budget to fight this problem, and has announced the start of the Pollinator Health Task Force. This group will work on keeping the US bee population healthy and strong, and will show people what they can do to help bees. Even though many people may not like bees, they are an important part of how we grow food. As pollinators , they move from one plant to another. Through pollination, plants can grow seeds and fruit. It's said that at least 90 kinds of plants including nuts,  fruits and vegetables depend on bees for pollination. The new Pollinator Health Task Force will work hard to protect bees, and build new hives for pollinators. It also plans to start a public education activity to make more people know the importance of pollinators, and actions that can be taken to protect them. The group will reach out to schools, libraries, museums and so on. Obama said that helping save the bee population will avoid other losses for the agricultural sector  , and will help protect the health of the environment. According to scientists,maybe the change of  _  has caused the problem of bees' disappearance.
time food weather their living environment