Давайте разберём каждый пример и выберем правильную форму глаголов "be" или "have", а также укажем соответствующее время.
Their son is a businessman.
- Время: Present Simple
He has a cassette.
- Время: Present Simple
These boys are students.
- Время: Present Simple
Much time is often spent by my relatives together.
- Время: Present Simple (Passive)
My friends will be introduced to my parents by me tomorrow.
- Время: Future Simple (Passive)
The museum was visited by them last Sunday.
- Время: Past Simple (Passive)
The examinations are seldom passed by him well.
- Время: Present Simple (Passive)
The library is rarely visited by the students last year.
- Время: Present Simple (Passive), но, судя по контексту, должно быть Past Simple (Passive), поэтому правильнее: "The library was rarely visited by the students last year."
The cake was cooked by my mother all evening yesterday.
- Время: Past Continuous (Passive)
Теперь пропуски заполнены, и для каждого случая выбрано правильное время и форма глагола.