the Internet brings much profit in, it can cause o lot of social problem. A. If

 _____ the Internet brings much profit in, it can cause o lot of social problem.
   A. If                    B. While              C. Once          D. When

试题答案

【解析】B 考查连词的辨析。依据句意来突破。从profit和problem发现前后对比转折，故选B