Update cheatsheet.en.md

10.temporary-m3p2/16.waves/20.n2/05.waves-introduction/10.waves-in-physics/cheatsheet.en.md

@@ -131,7 +131,11 @@ of the pond.
    *  *Reflection and transmission* at the interface between two different media.
    *  *Energy transport*, but *no matter transport* over long distances.
    
-   **are also found in more subtle phenomena** observed in nature and later described mathematically, or first predicted by physical theory before experimental confirmation.
+   **are also found in more subtle phenomena** observed in nature and later 
+   described mathematically, or first predicted by physical theory before experimental
+   confirmation.   
+   <br>
+   Thus, non-mechanical waves could be identified.
 
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