difficult coal造句

Japanese mining experts will help Australia develop more efficient ways to mine difficult coal deposits in its south-east, the New South Wales state government said Wednesday.
State Premier Bob Carr said the Department of Mineral Resources would join Japan's New Energy and Industrial Technology Development Corporation ( NEDC ) in a three-year, dlrs US 12 million ( dlrs Australian 15 million ) joint venture to find safer and more economic ways to mine difficult coal deposits in the Hunter and Gunnedah regions.
It's difficult to find difficult coal in a sentence. 用difficult coal造句挺难的