下列句中,代词“是”复指前置宾语的一句是()

A.句中句They told me that Professor Smith ______ here for twenty years by this winter.


B.前置I often hear him ______ about great writers.


C.宾语试述器官功能障碍的临床表现。


D.风险因素是风险事故发生的潜在原因,下列是造成损失的()。