1. Definition of Verb

 that “a verb is a word that does verb-y things.” He said the same thing about nouns (they do noun-y things) and other parts of speech as well, and while it’s not a very concrete or satisfying definition, it’s probably the best one out there.

You see, the way English works is that every word sits in a specific place and plays a specific role in a sentence. And even though a word might not really even be a real word, if it’s playing the role of the verb, then it’s a verb. Look at these examples:

·         As I phlomoggled my yard, I accidentally shallimped two birds.

·         Jack pazotors as often as he can.

·         They couldn’t believe she had never chorstined before.

·         This time next week, we’ll be forrisking through the jungle!

If you speak English fairly well, you can identify the verbs in those sentences even though they aren’t real words. You can do this because they are doing verb-y things. They have -ing, -ed and -s endings depending on when they happen and who is doing them. They also follow the subjects of the sentences and appear next to adverbs. And even though we don’t know what they mean, they somehow convey action. They behave like verbs.

2.       Definition of Modifier

A modifier is an optional element in phrase structure or clause structure.A modifier is so called because it is said to modify (change the meaning of) another element in the structure, on which it is dependent. Typically the modifier can be removed without affecting the grammar of the sentence. For example, in the English sentence This is a red ball, the adjective red is a modifier, modifying the noun ball. Removal of the modifier would leave This is a ball, which is grammatically correct and equivalent in structure to the original sentence.

Other terms used with a similar meaning are qualifier (the word qualify may be used in the same way as modify in this context), attribute, and adjunct. These concepts are often distinguished from complements and arguments, which may also be considered dependent on another element, but are considered an indispensable part of the structure. For example, in His face became red, the word red might be called a complement or argument of became, rather than a modifier or adjunct, since it cannot be omitted from the sentence.

3.            Example Sentence

A sentence is a group of words which starts with a capital letter and ends with a full stop (.), question mark (?) or exclamation mark (!). A sentence contains or implies a predicate and a subject.Sentences contain clauses.Simple sentences have one clause.Compound sentences and complex sentences have two or more clauses.

Sentences can contain subjects and objects.The subject in a sentence is generally the person or thing carrying out an action. The object in a sentence is involved in an action but does not carry it out, the object comes after the verb.For example:

Nisha Goes to Bali.

If you want to say more about the subject (Nisha) or the object (Bali), you can add an adjective.For example.

The sentence becomes more interesting as it gives the reader or listener more information.

sumber : http://grammar.yourdictionary.com/parts-of-speech/verbs/what-is-a-verb.html
http://en.wikipedia.org/wiki/Grammatical_modifier
http://www.learnenglish.de/grammar/sentencetext.html