What is a concluding sentence?
A Concluding Sentence is the last sentence of a paragraph(s), it
summarizes everything that you just wrote about and it is somewhat
like your Introduction Sentence.
Usually, your concluding sentence will say something like "In
conclusion," or "Therefore," or "To summarize."
Basically, when writing a formal paper, you have three steps --
"Tell them what you're going to tell them" (the Introduction),
"Tell them" (the Body), and "Tell them what you just told them"