_______ entering the classroom, remember to take your seat and turn off your cell phone.

The equipment for disabled people should be ______ easy reach in public places. 

In 1862 the American black people won their struggle____ equal rights after many years’ fighting ________ the white. 

A high official from the central government will come and explain ______ what the country has done to ensure to make the Football World Cup the best-ever game. 

—I’m going to have lunch. Do you mind talking about your plan ____ lunch?—All right. I’ll wait here in the office.