When my wife, who is a Spanish spent her first winter in London a few years ago, she used to ask me time and again, 'Where's the fog?' Almost all foreigners【C1】______to find the city wreathed in yellow-gray mist for most of the year. Dickens, who was.【C2】______responsible for painting this【C3】______in people's minds, certainly wasn't exaggerating in those days, People【C4】______in the nineteenth century that when someone.【C5】______suicide by jumping into the Thames he has chocked by the fog and poisoned by the terrible【C6】______of the river before he had time to drown himself. In fact, the situation【C7】______in recent years. When I was a boy in London city 30 years ago I was often unable to see【C8】______of the road when I left home on winter mornings. The decisive steps that have turned London into one of the【C9】______cities in the world【C10】______taken at the end of the 1950s. But Londoners still【C11】______that fog【C12】______returns. The change took place as a result of two main improvements. Factories are compelled to install clean equipment【C13】______close down, and private householders were not allowed to【C14】______coal unless it was smoke-free. But the【C15】______ecological miracle in London occurred【C16】______1964 onwards when the Thames Water Authority began to pump vast【C17】______of dissolved oxygen into the river.【C18】______, all the species of fish that had gradually disappeared from the Thames【C19】______1, 800 have returned. Some are even caught by fishermen【C20】______the House of Parliament. 【C1】