Let's sing
An apple a day
keeps the doctor awayAn apple a day
keeps the doctor awayAn apple a day
keeps the doctor awayA-P-P-L-E apple

fruit指“水果”时，为集体名词，只用单数，不用复数。如果指不同种类的水果或事情的结果时，则用复数fruits。
我们课文中出现的都是单数。

Do you like some apples?yes I do,
One for me and one for you.
Do you like some apples?yes, I do,
Two for dad and two for mum!