Они должны были вызвать врача, т.к.

Они должны были вызвать врача, т.к. их сестра была больна.
Занятие должно было начаться в 13.30, но преподаватель не пришёл.

Результаты (английский) 1:

They had to call the doctor because their sister was sick. Lesson was supposed to start at 13.30, but the teacher didn't come.

Результаты (английский) 2:

They had to call a doctor because their sister was sick.
Occupation was supposed to start at 13.30, but the teacher did not come.

Результаты (английский) 3:

they had to call a doctor, because. their sister was ill.class was set to begin in others, but the teacher hasn't come.