buy,fly等结尾是y的单词过去式是什么?

uy 的过去式是 bought
fly 的过去式是 flew
这些都是不规则变化
一般以辅音字母加y结尾的动词,去y加ied,
例子：tried; studied; justified; copied; carried; cried
注：不规则动词的过去式变化规律性不强,须多加记忆
例子: go - went; make - made; buy - bought; come - came; fly-flew