Question

___theory must be closely connected with practice is a basic rule we should always keep in mind

A.Why B.What C.That D.what

Answer 1

C
句子意思：
理论必须紧密和实践结合起来是一个我们应该永远记住的基本原则。

可以把句子结构调整为：
A basic rule we should always keep in mind is that theory must be closely connected with practice.

that 在这里做a basic rule 的先行词，引导后面的宾语从句。

Answer 2

C

追问

为什么呢？

追答

that 引导主语从句