It is often assumed that pre-schoolers learn a second language (L2) with ease, even for structures that are absent in their L1, such as Mandarin-speaking pre-schoolers learning L2 English grammatical inflections (e.g., duck s , hors es ). However, while the results from Study 1 showed that such learners can imitate plural words (age = 3;5, N = 20), Studies 2 and 3 showed that they cannot yet generate or comprehend plural morphology (Study 2: age = 4;8, N = 20; Study 3: age = 4;1, N = 20), raising questions about when this is achieved. These findings have important implications for school readiness, as well as for identifying those at risk of developmental language disorders.

人们通常认为学龄前儿童可以轻松学习第二语言 (L2)，即使是母语中没有的结构，例如说普通话的学龄前儿童学习 L2 英语语法变化（例如，duck s , hors es） . 然而，虽然研究 1 的结果表明这些学习者可以模仿复数词（年龄 = 3；5，N = 20），但研究 2 和研究 3 表明他们还不能产生或理解复数形态（研究 2：年龄 = 4； 8，N = 20；研究 3：年龄 = 4；1，N = 20)，提出关于何时实现的问题。这些发现对入学准备以及识别有发展性语言障碍风险的人具有重要意义。