(Чтобы дать более точные ответы, нужно видеть текст, по которому заданы эти вопросы. Поскольку текста нет, ответы даны на основе официальной биографии писателя)
Mark Twain was an American writer.
His real name was Samuel Langhorne Clemens.
He was born on November 30, 1835, in Florida, Missouri, the USA.
He began working in 1851.
His first profession was a typesetter.
When he was twenty, he became a printer (печатальщик). (When Clemens was 23, he became a pilot (лоцман).
In California he became a newspaper writer.
Mark Twain's experience helped him to become a writer.
Mar Twain's best known works are The Innocents Abroad, Roughing It, Life on the Mississippi, The Adventures of Tom Sawyer, Adventures of Huckleberry Finn.
I have read (The Adventures of Tom Sawyer)