Hints： 只听写例句。前面的单词不用听写。 这一期有两个例句哦。每一句都有一个连字符。
By 1880 a self-binding reaper had been perfected that not only cut the grain, but also gathered the stalks. Granite, for instance, is a coarse-grained igneous rock whose individual mineral crystals have formed to a size easily seen by the naked eye.