Question

You must work hard to pass the examination. Change it into compound sentence

Answer 1

To pass the examination hard work should be done by you

Answer 2

As per the rule compound sentence comprises of at least two or more co-ordinate clauses having their own subject and predicate. Instead of one subject and one predicate unlike simple sentence.  

Simple sentence: You must work hard to pass the examination.

Compound Sentence: You must work hard or you will not pass the examination.