同卵双胞胎50天孕囊图:请翻译成中文

The rich world's argument about the environment follows a pattern. Environmentalists say pollution is terrible and getting worse. Businessmen retort that a real clean-up would cost too much. The ordinary citizen believes both: the environment is indeed going down the drain, but so might his job if anyone tries to stop that. All of them, it turns out, are wrong.
Recent statistics show that, in rich countries at least, many of the worst pollution problems are far smaller than they used to be, and that the costs of this success have so far been small.
Start with air pollution. The dreaded greenhouse gases are still flowing into the atmosphere. But output of gases that attack the ozone layer is well under control. Production of CFCs (含氯氟烃)used in refrigerators has fallen by two-thirds since the mid-1980s. many pollutants have been beaten back. The flow of oxides of sulfur, which contribute to evils such as acid rain and smog, has fallen by around a third in rich countries since 1980. Emissions of lead, soot and carbon monoxide, each hazardous to human health, have also fallen sharply.
Water quality has Improved in many ways. there is still worry about chemicals, such as fertilizers and heavy metals, draining of the land. But many of the organisms that once infested (寄生于)rich-world waterways, and which still kill millions in poor countries, are retreating steadily. Progress is largely due to the spread of waste-water treatment.
Has this cost jobs? There is no evidence for that. Spending on pollution control amounts to 1%-2% of GDP (国内生产总值)in most rich countries, but that has not cut jobs overall. True, certain industries such as mining have lost jobs, and some companies have moved to less strict third-world countries. But greenery, like any new market, has also created jobs: the market world-wide was worth some $200 billion in 1990.
Much of this progress was due to market forces, not regulation. It took rules to keep lead out of petrol and smog away from London. But much of the fall in oxides of sulfur, for example, springs from the decline of coal-burning industries. Except for waste-water treatment, most improvements have come fairly cheap. Either inexpensive alternatives already existed or cheap gadgets(机械装置)could be added to existing machinery.
Some regulation has gained support because it protects vested interests(既得利益者). The rich countries' ban on CFCs, for example, is backed by big chemicals firms that are eager to create a market for their substitutes.