This new kind of chemicals will help keep the air, soil and water________ from pollution.
Those _____ to go to the exhibition should inform the office.
There were many more people who got injured in the big fire than _______.
_____ of water makes Death Valley a desert, but it is by no means devoid.
There are some police cars in front. What do you suppose _____?
The great use of school education is not so much to teach you things ____ to teach you the art of learning.