>> slahi: almost none. >> williams: in the office of his new apartment in mauritania, mohamedou slahi us how he learned english in guantanamo. he reads and writes his fourth language with some help from the u.s. navy. where did you get those glasses? >> slahi: these glasses i got from navy hospital in guantanamo bay. thank you, doctors. and they had choices. and i took the ugliest one. >> williams: you-- you chose the-- >> slahi: as a sign of protest. >> williams: he was his own teacher in guantanamo, soaking up new vocabulary wherever he could. >> slahi: i'm letting you now into my world. okay, this how i learn the english language. this is the original. >> williams: so-- so you would, what, hear something, and write it down? >> slahi: hear something, write it down, and ask. >> williams: and then ask a guard? >> slahi: yes, a guard, or an interrogator. >> williams: "how do you spell that?" >> slahi: whomever i meet, whomever i meet. >> williams: yeah. "to chortle." >> slahi: "to chortle." >> williams: that's-- that's a very-- that's a very good-- >> slahi: "snorting a joyful laugh."

. >> mohamedou slahi was a sworn member of al qaeda and spent nearly 14 years as prisoner 760