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 third person 2 Regular past 3 Regular plural 4 Present progressive 5 Possessive ‘s’ 6 Irregular past 26-48 25-46 19-28 28-50 27-33 26-40 1 Early I 2 Late II 3 Late I 4 Early III 5 Late III 6 Early II 12-22 33-34 31-32 27-28 28-30 22-26