请帮我找出这里面的从句以及谓语动词的形式

Mark Twain,whose original name was Samuel Clemens（定语从句）,is an important figure in American literature.Speaking（现在分词） of short stories alone,Mark Twain’s position in American literature is as Chekhov’s is in Russian literature or Guy de Maupassant’s in French literature.Even in his own day,Mark Twain was seen as one of America’s most famous writers.
At 13,Mark Twain was learning to be a printer（不定式）.Eight years later he began to learn（不定式） to work（不定式） as a steamboat pilot.In 1865,he wrote the story The Celebrated Jumping Frog of Calaveras Country,which made him famous（定语从句）.In the following years,he travelled widely as a successful lecturer and gathered material for his writing（动名词）.His humorous short story The Innocents Abroad and his youthful adventures,The Adventures of Tom Sawyer,The Prince and the Pauper and The Adventures of Huckleberry Finn helped him win a worldwide audience.At the same time he became a well-known humorist.

　　Mark Twain,（whose original name was Samuel Clemens）（whose引导的定语从句）, （is）（be动词一般现在时） an important figure in American literature. Speaking of short stories alone, Mark Twain’s position in American lite...