This new kind of chemicals will help keep the air, soil and water________ from pollution.
It was along the Mississippi River ________ Mark Twain spent much of his childhood.
Linda,make sure the tables ________ before the guests arrive.
________caused the accident is still a complete mystery.
—May I borrow your computer? —Sorry, it is ________ at the moment.
Eugene's never willing to alter any of his opinions.It's no use ________ with him.