7．(2014·全国卷Ⅰ)Finally, that hard work paid off and now the water in the river is ________ (clean) than ever.

　　解析：cleaner　从后面的"than"可知此处要用形容词比较级，故填cleaner。

　　8．(2014·广东高考)After our plane landed, we went to the hotel.We had made our reservation six months ________ (early), but the man at the front desk said there had been a mistake.

　　解析：earlier　由"had made"可知该动作发生在到达旅馆之前，故应该是早在六个月之前我们就已经预订了，所以用副词比较级earlier。

　　Ⅱ.单句改错

　　1．(2018·全国卷Ⅲ)I was afraid to speak in front of a larger group of people.________________

　　解析：larger→large　根据句意，作者害怕在一大群人面前讲话，这里没有比较的含义，故将larger改为large。

　　2．(2017·全国卷Ⅱ)They often get up earlier and water the vegetables together.________________

　　解析：earlier→early　get up early意为"早起"，句中没有比较的意思，故不用比较级。

　　3．(2016·四川高考)The dishes that I cooked were Mom's favoritest.________________

　　解析：favoritest→favorite　favorite没有比较级和最高级。

　　[谨记规则]

　　(一)形容词和副词比较等级的构成规则

　　1．规则变化

构成 例词 原级 比较级 最高级 单音节的词一般情况下直接加­er和­est small smaller smallest great greater 　　greatest hard harder hardest 以不发音的e结尾的单音节词加­r和­st nice nicer nicest