I am having trouble understanding pronouns, predicate nominatives, direct objects, indirect objests, and object of prepostion. I don't know how to tell them apart. What's an easy way to undertstand them?

First, I suggest you memorize the most common pronouns and prepositions.

http://www.google.com/imgres?imgurl=http://www.widgit.com/widgitrebus/images/pronouns3.gif&imgrefurl=http://www.widgit.com/widgitrebus/rebus_html/pronouns.htm&h=407&w=735&sz=12&tbnid=7_wc_fqkP5A3NM:&tbnh=78&tbnw=141&prev=/images%3Fq%3Dpronouns&hl=en&usg=__uvlT1hiuGH9J_tAqPdRMlwNi5n4=&ei=VywoS_nNIZTllAfE3amqDQ&sa=X&oi=image_result&resnum=8&ct=image&ved=0CBoQ9QEwBw

http://www.englishclub.com/grammar/prepositions-list.htm

Then study this site carefully.

http://grammar.ccc.commnet.edu/grammar/objects.htm

The object of a preposition always follows a preposition.

In short, there's no "easy way" to understand these complex sentence parts without a lot of study and practice.

Understanding pronouns, predicate nominatives, direct objects, indirect objects, and objects of prepositions can sometimes be confusing, but with a bit of practice and knowledge of their functions, you can easily tell them apart. Here's a breakdown of each:

1. Pronouns: Pronouns are words used in place of nouns. They can refer to a person, thing, or idea. Examples include "he," "she," "it," "they," "we," "you," and "I." To identify pronouns, look for words that replace nouns in a sentence. For example: "John is hungry. He wants pizza." In this case, "he" is a pronoun referring to John.

2. Predicate Nominatives: A predicate nominative is a noun or pronoun that follows a linking verb and renames or identifies the subject of the sentence. To identify a predicate nominative, start by identifying the linking verb (e.g., "is," "are") and then look for the noun/pronoun that comes after it, providing more information about the subject. For example: "She is a doctor." In this case, "doctor" is the predicate nominative renaming the subject "she."

3. Direct Objects: A direct object receives the action of a verb. To identify a direct object, first locate the verb in the sentence. Then ask yourself who or what is receiving the action of that verb. The answer to that question is the direct object. For example: "John kicked the ball." In this sentence, "ball" is the direct object because it receives the action of the verb "kicked."

4. Indirect Objects: An indirect object is a noun or pronoun that receives the direct object and usually tells "to whom" or "for whom" something is done. To identify an indirect object, follow these steps: find the action verb, locate the direct object, and then ask "to whom" or "for whom" the action is done. The answer to that question is the indirect object. For example: "She gave John a gift." In this sentence, "John" is the indirect object because the gift is given "to" him.

5. Objects of Prepositions: Prepositions are words that show relationships between nouns/pronouns and other words in a sentence. The object of a preposition is the noun or pronoun that follows the preposition and is connected to the rest of the sentence. To identify the object of a preposition, locate the preposition and ask "whom" or "what" after it. The answer is the object of the preposition. For example: "The cat is on the table." In this sentence, "table" is the object of the preposition "on."

Remember, practice is key when trying to understand these concepts. By breaking down sentences and carefully identifying the functions of words, you can gradually improve your understanding of pronouns, predicate nominatives, direct objects, indirect objects, and objects of prepositions.