A lot of tents, drinking water and food ______ to the homeless earthquake survivors in the past several weeks.
This new kind of chemicals will help keep the air, soil and water________ from pollution.
Barack Obama has taken personal blame ________ the security failures which led ________ the attempt to blow up a plane on Christmas Day.
―Look! What a mistake! Why?―Sorry, I _________ on it.
My father didn’t have to say anything.I knew he was upset from his ________.
Cao Cao’s tomb is reported ________ in China, which attracts nationwide attention.