The sentence consists of a main clause and a subordinate clause.

这中有一个主和一个从。

Linguistic indices contain the ratio of error-free T-unit (REFT) and subordinate clauses per T-unit (SCT).

语言指标包括无错T-单位与全部T-单位之比(REFT)和全部从与全部T-单位之比(SCT)。