was served over the counter" is a sentence because it is a complete thought that includes a subject ("I") and a verb ("was served").
"The book is for him" is a sentence because it is a complete thought that includes a subject ("book") and a linking verb ("is") followed by a predicate noun ("him").
"Give the book to Kofi" is a sentence because it is a complete thought that includes a verb ("give") and a direct object ("book") with an indirect object ("Kofi").
"Give hile opened it with a knize" is not a sentence because it is incomplete and contains errors. The word "hile" is likely a typo and should be replaced with "while". The phrase "opened it with a knize" is also incomplete and lacks a subject. To make it a sentence, it could be rephrased as "While he opened it with a knife, he accidentally cut himself."