问题
选择题
Rain is pouring down from the sky without any sign of stopping．Farmers begin to worry about their crops since it _____ as long as 24 hours．
A．would rain
B．had rained
C．was raining
D．has been raining
答案
答案：D
考查时态。句意：雨水从天空倾盆而下，没有一点停的迹象。由于雨一直不停的下了24个小时了，农民们开始担心他们的庄稼。结合语境可知下文描述的是现在已经完成的正在进行的动作，故用完成进行时，选D。