He didn’t _________ me and lent me some money when I lost my job.    

. The United States of America ________ 50 states.      

He ­­­_______ himself as a police officer.

Mike _______ in touch with his former schoolmates, who had been living there for ages
as soon as he arrived in America.

If you _______ with your classmates, you will surely get the same work done far
better.

It _______to John that he had left the door unlocked.

Newly-developed materials for spaceships can _______ extreme weather conditions.

Don’t ________ women. They are as important as men for the development of society.

Try to be more careful next time. Carelessness only________ mistakes.

The most serious problem we are facing now is how to ______ all the pollution.