19. One of the most unusual animals in the world,eggs are laid by the platypus,which is also a mammal.
the platypus is a mammal that also lays eggs.
20.The unique culture of Cork is primarily founded by its great musical and lyrical traditions.
Cork has a unique culture founded primarily on
21. Having an exceptional beautiful mountain range and heavy winter snowfall,the International Olympic Committee choose Salt Lake city as the site of the 2002 Winter Olympics.
Because it has an exceptionally beautiful mountain range and heavy winter snowfall,Salt Lake city was chosen by the International Olympic Committee
点评：一种常考题型，因果关系的反映。由于Because的后面的it指Salt Lake city,故后半句主语开头必为Salt Lake city。
22.The marathon runner’s early burst of speed had been exciting to some,she was slower after several miles.
had been excitihg to some;however,she was
23.(常考题：对比)The annual income of the average African citizen is 211 dollars,the average American’s income is almost 27591 dollars.
dollars,yet the average American’s income is
24.Although the CWS win more often than the CC,Chicago residnets,who are historically mid(此处不清晰) baseball fans,prefer the CC。