When verbs or nouns end with ch, sh, x, o, ss or zz then we add 'es' at the end of those verbs or nouns .
When above mentioned letters do not occure at the end of words, we add 's' to make them plural.
There is a Solecism in Present Indefinite where we have to add S or ES with the first form of verb. In South Asian contries like Pakistan, India, Sri Lanka, Bangladesh etc Present Indefinite tense is mostly taught on the basis of numbers i.e singular and plural. Typically it is taught that S or ES is added to first form of verb when subject of the sentence is singular i.e (He, she, it, singular names) and S or ES will not be added to the first form of verb when subject of the sentence is plural i.e (I, we, they, you, plural names). It is alright with students and their studies because they feel no hindrance in making sentences of this tense with above mentioned formula because every thing falls according to the established rules of grammar. They have not to face any grammatical errors by using this singular plural technique in their writings. But conceptually students are not up to the mark when they are asked why S or ES is not added to the verb when pronoun I is singular.<>
It is wrong depite I is singular. Then they are unable to answer this why.
Actually Present Indefinite tense must be taught on the basis of persons instead of numbers. Students should be taught that S or ES is added to the first form of verb when subject of the sentence is third person singular i.e (He, she, it, one, singular names) and S or ES will not be added to first form of verb if subject of the sentence is 1st person, 2nd person or 3rd person plural i.e (I, we, they, you, plural names).
There are three persons in every language and so has English.
The third person includes pronouns like he, she, it, one and all singular nouns i.e inanimate things, people, concepts, animal etc. This 'S' added to the third person singular of simple present is used only in English. It is not used in French, German, Italian or other languages and it is actually called 'The third person singular S'.