How to add items From Combo Box Transferred to RichTextBox using Enter Key?

How to add items From Combo Box Transferred to RichTextBox using Enter Key?

References

Reference NO 1

http://stackoverflow.com/questions/15199650/how-to-add-items-from-combo-box-transferred-to-richtextbox-using-enter-key

Reference NO 2

http://stackoverflow.com/questions/15242567/how-can-i-add-text-from-combobox-down-to-richtextbox

Reference NO 3

http://stackoverflow.com/questions/18129003/winform-richtextbox-get-last-character-entered-using-c-sharp

Reference NO 4

http://stackoverflow.com/questions/17314742/find-words-or-sentence-from-a-richtextbox-and-add-into-a-list-c-sharp

Reference NO 5

http://stackoverflow.com/questions/15170903/hidden-listbox-will-appear-while-typing-words-in-richtextbox

Reference NO 6

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Reference NO 7

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Reference NO 8

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