Research on its acquisition difficulty mainly focuses on two aspects: relative clause type and matrix position.

而对它的习得难度研究主要集中在两个层面，即从句类型和从句位置。

youdao

Research on its acquisition difficulty mainly focuses on two aspects: relative clause type and matrix position.

而对它的习得难度研究主要集中在两个层面，即从句类型和从句位置。

youdao