There are quite a few plagiarisms checker tools online. Some of them are quite effective and is popular for providing research paper help. Undoubtedly, this is the best way to detect and correct plagiarised content.
This is a nice trick the professionals use while providing an assignment problem solution. If you feel that including a certain sentence is necessary for your essay paper, include that within a quote. This is the best and safest way to avoid any negative consequences. However, you must be aware of the citation rules before quoting anyone.