Shuang is the measure word for pairs. English is pair of pants but Chinese requires "tiao ku zi". Why does the English translation include pair of pants. It should be "Those pants are too big". Just makes it more confusing than need be.
Duolingo, please, in the exercises where we need to recognize the characters with pinyin, I would appreciate to have also there the meaning of each character... it will help a lot. I write here, because it is impossible to write a comment in those exercises.