已知等比数列$\left\{a_n\right\}$，它的前$3$项为$1,2,4$，前$n$项和为$S_n$，则使得$S_n=127$的$n$的值是（    ）

指出下列各句修辞方法错误的是（   ）。

短文改错。

    Jim Green teaches our ____ English. He has been in China for more than two year____. He has been to many interesting places in Beijing, and____  he has not yet been to many others ____ parts of China. Last week he goes ____ to Mount Emei in Sichuan Province with his family. Many people like travel ____ by air, but Jim ____ family think that traveling by train is the best. It is much cheap ____ and far more enjoyable than a rushing trip by air. He ____ had a wonderful train ride to Chengdu after ____ they went to Mount Emei by bus.