From his ____ voice on the phone, I know everything is going under way. 

Pleasant music is often played       classes to make students refreshed and relaxed for a while.

Nowhere else _____ be able to find a larger display of sea animals, including one of the largest collections of sharks in the world.

A plan has been put forward __ more graduates should go to work in the country

  —I think everyone has a role to play in making the planet a better place.—Yes, indeed. ______.