Australian scientists are trying to give kangaroo-style stomachs to cattle and sheep in order to cut the greenhouse gases they send out, which is thought to be responsible for global warming.

　　Thanks to special bacteria in their stomachs, kangaroo flatulence (肠胃气胀) contains no methane and scientists want to transfer that bacteria to cattle and sheep who produce large quantities of the harmful gas.

　　While the usual image of greenhouse gas pollution is a billowing smokestack, pushing out carbon dioxide, farm animals’ passing wind contribute a surprisingly high percentage of total emissions in some countries.

　　“Fourteen percent of emissions from all sources in Australia are from enteric methane from cattle and sheep,” said Athol Klieve, a senior research scientist with the greensland state government. “And if you look at another country such as New Zealand, which has got a much higher agricultural base, they are actually up around 50 percent,” he said.

　　Researchers say the bacteria also make the digestive process much more efficient and could potentially save millions of dollars in feed costs for farmers. But it will take researchers at least three years to isolate the bacteria before they can even start to develop a way of transferring it to cattle and sheep.

　　Another group of scientists, meanwhile, have suggested Australians should farm fewer cattle and sheep and just eat more kangaroos. And about 20 percent of health-conscious Australians are believed to eat the national symbol already.

　　It’s low in fat, it ’s got high protein levels and it is very clean in the sense that basically it is free-range(放养的) animal,” said Peter Ampt of the University of New South Wales’ institute of environmental studies.

　　28. Scientists intend to put bacteria into cattle and sheep________.

　　A. to help Australian farmers to earn more money

　　B. to prevent them from sending out harmful gases

　　C. so that they can protect Australian ecosystem

　　D. so that they can make full use of special bacteria

　　29. Athol Klieve seems to believe that _________.

　　A. farm animals are to blame for greenhouse gases

　　B. less cattle and sheep are raised in New Zealand

　　C. cattle and sheep produce less carbon dioxide

　　D. New Zealand has the most animals in the world

　　30. The advantages Peter Ampt lists about kangaroos don’t include ________.

　　A. it is rich in protein

　　B. it is low in fat

　　C. it is cheaper than beef

　　D. it is cleaner than sheep

　　31. The main idea of the passage is to ________.

　　A. discuss a better way to protect the earth

　　B. warn farmers of the danger of animal waste

　　C. explain the possible solutions to pollution

　　D. present a recent study on global warming

　　【答案】BACD