Correct these sentences better. please i already tried the best.?

Question

1) To learn the job, Clemens spent more than two years as a cub, river boat slang as an apprentice.

2) Clemens, who wrote under the pen name Mark Twain, later said that life on the river introduced him to every possible type of human nature.

thank you !!

Answer 1

Clemens spent over two years as a cub, or apprentice in river boat slang, to learn the job.

After writing under the pen name Mark Twain, Clemens said that life on the river introduced him to every possible type of human adventure.

Answer 2

(Trying to make minimum changes)
1. To learn the job, Clemens spent more than two years as a cub (river boar slang for 'apprentice').
2.This sentence seems to be fine. If possible, you can place the words Mark Twain within italics or between apostrophes.