nineteen;
例句:
The British Empire flourished in the 19 th century.
英帝国在19世纪曾昌盛一时.
She was 19 when she lost her virginity.
她十九岁时就失了身.
The 19 th century was the heyday of steam railways.
19世纪是蒸汽机车鼎盛的时代.