The constraints concerned here are two UG principles — Subjacency and Empty Category Principle (ECP).

这限制条件指的是承接原则空范畴原则。

The two main principles of the theory adopted in this paper are the Subjacency condition and the ECP, which will help us to know better of the idea we are introducing here.

本文认为汉语中生成语法文献中所论述的接应代词相同的现象，进而帮助我们深入认识汉语的某些句法性质。