给定一段英文文字和一个单词，将文本中包含该单词的所有句子用该单词替换掉。
待替换的文字: This is a sample text. It contains multiple sentences. The word "sample" appears in this text.
待替换的单词: sample
This is a sample text. -> This is a sample.

It contains multiple sentences. -> 

The word "sample" appears in this text. -> The word "sample" appears in this sample.