【题目】The last few years ___ the worst period on record for environmental disasters and experts are predicting far worse to come.
A. see B. saw
C. have seen D. are seeing
在线课程【答案】C
【解析】考查时态；根据句意“最后这几年见证了历史上环境灾害最严重的一段时期，专家预测，接下来情况会更糟糕”可知，“the worst period on record for environmental disasters”是现在已经发生了的动作，所以用现在完成时，故选C.