问题补充：
The factory its waste into the river, but now it deals with the waste in a new way.
A. used to dump
B. is used to dump
C. used to dumping
D. is used to dumping
答案：
(答案→)A. used to dump
B. is used to dump
C. used to dumping
D. is used to dumping
解析：考查used to的用法。句意“工厂过去常常把废水排进河里，但是现在，它用一种新的方法来处理废水。”used to do sth.“过去常常做某事”；be used to doing sth.“习惯于做某事”；sth. be used to do sth./for doing sth.“某物被用来做某事”；sth. be used as...“某物被用作......”。故选A。
