㈠表示世上唯一的事物,如:
①the sun;the earth;the sky;the North Pole
㈡当一个名词被再次提起时,如:
②A car knocked against a tree.We can still see the mark on the tree made by the car.
㈢当名词后面有个修饰作用的短语或分句时,如:
③The girl in red is my sister.
④The thief who stole your wallet yesterday was arrested.
㈣加在某些形容词前面,以表示某类人或事,如:
⑤The rich often get richer and the poor,poorer.
⑥The doctor lost no time in giving help to the injured.
⑦Don't expect the impossible.
㈤加在某些山川、河流、岛屿、国家名称之前,如:
⑧the Alps;the Thames;the British Isles;the Philippines;the Atlantic Ocean.