问题补充:
Over the past l00 years,sea levelsteadily as a result of global warming.
A. had increased
B. has been increasing
C. increased
D. is increasing
答案:
A. had increased
(答案→)B. has been increasing
C. increased
D. is increasing
解析:考查时态,句意:在过去的100年中,作为地球变暖的结果海平面一直在稳定的上升。可知本句描述的是现在已完成的一直在进行的动作,故用完成进行时态。选B。