It was incumbent on them to attend.

他们必须出席。

《牛津词典》

He is due to attend the opening of the Asian Games on Saturday.

他定于星期六出席亚运会的开幕式。

《柯林斯英汉双解大词典》

There are no compulsions on students to attend classes.

没有强求学生上课。

《牛津词典》

It is also common for teachers to spend a not insignificant amount of their own money on materials for their students and there are at least a few training sessions they are expected to attend during the summers (on their own time).

FORBES: Why US education deserves our praise (and funding)

He will travel on from Cuba to Peru where he will attend the Apec (Asia-Pacific Economic Co-operation) summit in Lima on 21 and 22 November.

BBC: China signs trade deals with Cuba

Five hundred people are expected to attend the event on Sunday called Y Bont (The Bridge).

BBC: The Trefechan bridge protest in 1963