There are cases in which "to be" is translated with 是 ( shì ), while in some other cases it seems not to be translated at all. When should 是 ( shì ) be used? When omitted?
Here some examples: 我很好 wo hen hao I am very well
我是英国人 wǒ-shì-yīng-guó-rén I am English
Wo hen kuai le 我 很快乐 I'm happy
我 25 岁 了 Wǒ èrshíwǔ suì le I'm 25 years old
Disambiguation 1: I landed in a similar question: When should I use the 是...的 construction? Note that it addresses the usage of 是 and的 !
Disambiguation 2: This question has been marked as oossible duplicate of: Why is (是) shi4 dropped in this sentence："我很好"?
Indeed the subject is similar. I think that this question is more General, while the other targets a specific case (I was not able to find it before posting my question!). To be noted that some answers are quite similar.