这个that if是什么意思

这个that if是什么意思
 
这道题中的 that if 是什么意思？
She promised _________ he had enough money she would marry him.
A. that                    B. if                     C. that if                 D. if that
【分析】此题应选 C，其余几项均有可能误选。句子的正常词序为 She promised that she would marry him if he had enough money. 由于将条件状语从句 if he had enough money 插入动词 promised 与其宾语从句之间，从而导致许多同学误选。顺便说一句，本来动词 promise 后接宾语从句时，引导宾语从句的 that 是可以省略的，但是按英语习惯，当动词与其宾语从句之间插有其他成分时，引导宾语从句的 that 通常不宜省略，所以此题不宜选B。又如：
She promised that if anyone found her son she would give him a lot of money. 她答应要是谁找到她儿子，她会给他一大笔钱。（句子可改为 She promised that she would give him a lot of money if anyone found her son.）
He said that when his wife came back he would leave. 他说等他妻子一回来，他就离开。(句子可改写为 He said that he would leave when his wife came back.)
Tell him that if he is at home I’ll come to see him. 告诉他，如果他在家，我就去看他。(句子可改写为 Tell him (that) I’ll come to see him if he is at home.)