题目内容：

i'm moving to the countryside because the air there is much fresher than { }in the city.
a.ones b.one c.that d.those为什么选择c
cars do cause us some health problems ---in fact far more serious{ }that mobile phones do.
a.one b.ones c.it d.those
为什么选择b 综合分析俩题谢谢

优质解答

上文已提及的事物 如the air 和problems 下文再提及时用one（复数ones）或that（复数those）.若用one则表示这个提及到的事物的同类,但并非提及的那一个,如：Your new pen is nice,I want to buy one.表示要买的是另...