Here's why:
* Imperative sentences give a command or make a request. They usually begin with a verb and often end with a period or an exclamation point.
* Interrogative sentences ask a question. They usually begin with a question word (who, what, when, where, why, how) or an auxiliary verb (do, does, did, etc.).
* Fragments are incomplete sentences that lack a subject or a verb.
* Run-on sentences occur when two or more independent clauses are joined together without proper punctuation or conjunctions.
In this case, "Touch the package" is the command, and "please" is added for politeness.