into use in April,2000,the hotline was meant for residents reporting water and heating supply breakdowns.
A.Put B.Putting C.Having put D.Being put
into use in April,2000,the hotline was meant for residents reporting water and heating supply breakdowns.
A.Put B.Putting C.Having put D.Being put
A
考查过去分词作状语。句子的主语是the hotline与“投入使用”存在着被动关系,而且表示过去的事情,所以排除D项。