In general, the conjugation of verbs in the present simple is not very complicated. While other languages may often have many different verb forms for all grammatical persons, most verb forms in English remain unchanged.
Adding 's' in case of 'he, she and it'
English learners just need to be careful using the third person singular in the present tense (which corresponds to "he, she, it"). In this case, "s" or "es" is added to the infinitive of the verb.
1. "S" is added to the verbs following "he, she, it" in the present simple, examples:
- Sara needs to study. → (she)
- She buys bread every day.
- Adam loves sport.→ (he)
- He works at nights.
- The cat drinks milk. → (it)
- It drinks milk.
- My teacher speaks 4 languages.
2. Add "es" to the verbs ending in "sh, ch, s, ss, o, x, zz", examples:
- Aya goes to school every day.
- Ahmed washes his car on Sundays.
- She teaches History in the morning
3. In case a verb ends with a consonant "y", the "y" is replaced by "ie" and an "s" is added, examples:
- My husband flies to London every week. → (to fly)
- The baby cries a lot. → (to cry)
A verb ending with a vowel "y" keeps its "y":
- She always buys too many clothes. → (to buy)
4. The modal verbs ("can, may, must", etc.) are invariable and so never end with an "s" – not even in the third person singular, examples:
- She can swim very well.
- Peter must stay at home.
- It may be a good idea to do that.
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References