The school rules state that no child shall be allowed out of the school during the day, ________ accompanied by an adult.[ ]

There are over 58000 rocky objects in ______space，about 900 of which could fall down onto ______ earth.

I’d like to go to the cinema with you, Dad. — Sorry, my darling, but the film is ____ for adults only.

It was the dream of becoming rich _____ attracted people from all over the world to the state, ______ gold was discovered in 1848

The teacher _______some old friends on hisvacation trip to Paris.