Questions & Answers about Этот телефон мой.
In Russian, the verb to be is usually omitted in the present tense.
So Russian says:
Этот телефон мой
literally: This phone mine
But it means This phone is mine.
This is completely normal. In the past or future, forms of быть do appear:
Этот телефон был мой = This phone was mine
Этот телефон будет мой = This phone will be mine
Because телефон is a masculine singular noun, and этот has to agree with it.
Russian words like this change form depending on gender and number:
- этот = masculine
- эта = feminine
- это = neuter
- эти = plural
Since телефон is masculine, you say этот телефон.
Compare:
- этот телефон = this phone
- эта книга = this book
- это окно = this window
- эти телефоны = these phones