第一句,讲的是过去的情况对吧?所以要用过去式.
而第二句,有一个句型:no sooner than,意思是“一……就……”主语用过去完成时,than后面的用过去式,这个是固定的用法,需要你记一下.Not only was the city polluted but the streets were crowded.为什么此处不用did???这里是被动的,所以用的是was+动词过去式。如果此处是主动,即用Did???对的。是主动就用did,so small were the words that he could hardly see them.为什么用were不用did???你可以把语序换成陈述句再来看看,Thewordsweresosmallthat……。懂么?