within five years,more colour than black-and-white TV sets were being used
问题描述：
within five years,more colour than black-and-white TV sets were being used
这是课本中原句,为什么用were being used?详细说明理由
答
首先意思是: 近五年来彩色电视要比黑白电视机用得广
从句子的时态看出,从说话的这一刻起彩电与黑白电视使用的状态还在进行中, 所以用Being
而另外又是从过去到现在的五年内故用Were
再补充一点电视是被用来看的故用 being used