Writefull is a weird application as helpful as it is. It can tell you if your sentences are written in a strange way: if you tell Google's similar search results
So if you select a sentence in your text and the application does not return any results, it means that there is a problem with the sentence and you have to correct it.
The best way to get thousands of results is to search continuously. This simple application lets you do more than one search at the same time, and uses asteroids as air cards for larger search.
If you need it, you can see synonyms for enriching your text. To open different sections of the interface, you need to press the Control key and Spacebar at the same time.