A、Londoners and the Thames. B、The Clean Air Act. C、Other measures. D、The Clean Air Act and other measures. BWhat legislation hel

London is a city sitting on a meandering river, with palaces overlooking barges sailing on the clear water of the Thames. Each year the Cambridge and Oxford boat race is run on the river. Such a boat has eight oarsmen, each using an oar of 3.7 metres. A trained crew can work up great speed and shoot away like a rocket. The victor of the race is front-page news of the evening paper.
    Many bridges span the Thames in London. Of these the most famous is probably the Westminster Bride. If you hap- pen to be in London one of these days, do take a look from that bridge. On your right you will see the House of Commons and the House of Lords, and the Big Ben, which strikes every quarter of the hour. In the busy traffic on the bridge, you will notice the red double-decker buses, which roll past quite smoothly in spite of their huge bodies. Two bridges, the Waterloo Bridge and the London Bridge, are visible in the distance.
    Fifty years ago London suffered from smoke and fog. Londoners called it pea-soup fog, because it looked so thick. Today the smog is gone, and the air remains clean, and fish has returned to the Thames, thanks to the Clean Air Act and other measures.