Thousands of years ago，human(人类)didn’t live in towns．Sometimes they would live in caves(洞穴)or build camps in the forest．
Only about thirty people1 in each camp．The men would go hunting while the woman and children2food from trees around the camp．All the food was 3 among people in the group．Every few weeks they moved to another place to find more food．It was a simple life，but people had to be 4 .They had to make everything that they needed，and they had to know a lot about plants and animals．
Nowadays most people live in towns and cities，and they work in offices and factories．Life is 5than in the old days．There are fewer 6，but there is less excitement．Some people go7  excitement  sailing round the world．climbing mountains，or exploring(探测)caves．
Most people look forward to the8,a time when they can enjoy a change from the normal life．For some this means going camping．But camping today is 9 from camping in the past．Gas cookers，ready-made food and air-beds mean people can camp much more10 than they did in the old times．

根据短文理解，回答下列各题。

      CCTV reported that every year Chinese people throw away a lot of food; it can feed 200 million people for a year.

      Do we have too much food? Of course not. According to the UN World Food Program, there were 925 million hungry people around the world in 2010. Six million children die of hunger every year.

      Luckily, a number of people have realized the importance of saving food. Last November, Li Hong, a waitress in a restaurant in Nanjing, lost her job because she took some leftover(剩余的)food home for her son. Many people are by her side and criticized(批评)the waste behavior.

      What should we do in our daily life to waste less food? Here are some tips:

       ①Don't order too much food in a restaurant. Only order as much as you want to eat. If you cannot eat all the food you order, take the rest of it home.

       ②Don't be too picky(挑剔的)about food. Some food may not taste great, but your body needs it.

       ③Don't keep too much food at home, especially vegetables and fruit.

     “Every grain on the plate comes from hard work(谁知盘中餐, 粒粒皆辛苦).” It tells us everybody must save food.

根据句意, 用适当的介词at, about, like, with或 for填空, 完成句子。

下列我国的世界遗产中，全部属于自然遗产的是（   ）