我们举例来说明。
do: did, done
excite: excitement, excited, exciting
interest: interested, interesting
wash: washing, to wash, washed, have washed, be washed.
She is washing her clothes.
She needs to wash her clothes.
Her clothes was washed by her mom.
She has washed all her clothes.
由以上可以看出,英语单词中有些词它有不同的形式。