根据短文内容从方框中选择恰当的单词填空，使短文完整、通顺，有的需要变换形式。

lesson，subject，because，tired，I

    Hello，everyone!  name is Li Hua．I am 13 years old．I've got six  at school．And my favourite is maths．I have three in the morning and two in the  afternoon．I am  but I am very happy  I can learn a lot．