It is requested that each of the teachers invited      a performance at the party.

Cars play an important role in modem life, but they       also cause many problems like air pollution.

 It is required in our school that lights in students’ rooms ______ off by 11o’clock.

Whenever the teacher was not here,the children       make a lot of noise.

She got stuck in a traffic jam on the way, or she    dinner with us now．