Despite nods to American English, the default spelling is British (colour, centre, travelled). The listening exercises (in the audio version) feature predominantly UK accents. This can confuse learners targeting the US market.
Mastering the Basics: A Guide to English Vocabulary in Use – Elementary English Vocabulary In Use -Elementary-
Repeat this 5-step system for every unit. Do one unit per day (or three per week). Do not rush. Despite nods to American English, the default spelling