Matching Pairs Brown’s MLU stagesOnline version Test yourself on Brown’s research on morphological acquisition by matching pairs of morphemes with the month age of mastery. by Som Person 1 Regular past 2 Regular third person 3 Present progressive 4 Possessive ‘s’ 5 Irregular past 6 Regular plural 28-50 25-46 27-33 26-48 26-40 19-28 1 Early I 2 Late I 3 Late III 4 Late II 5 Early II 6 Early III 27-28 28-30 33-34 22-26 31-32 12-22