Объясните значение глагола " быть". i am a student of the institute of foreign languages. we are reading the text now. she is to come in time. my friend is 20. she is very attractive.

I am (глагол-связка) a student of the Institute of Foreign Languages. We are (вс глагол в наст. продолж. времени) ) reading the text now. She is (часть эквивалента модального глагола) to come in time. My friend is (глагол-связка) 20. She is (глагол-связка) very attractive.