根据汉语提示填出正确的单词形式。（一空一词）
The river has been _______ (污染) by waste from local factories.
It is a pity that the industrial cities built in the 19^th century do not________(吸引) visitors.
Improving the city’s public transportation system is one of the _______ (挑战) Ms. Garvey now faces.
He ________ (折叠) the map up and put it in his pocket.
We hired a local ______ (向导) to get us across the mountains.