Today is a Sunday.(去掉a) It is very hot.My mother and I are goingto
（are goingto改成went,用過去式） a bookshop.There are some books in the bookshop.I like interesting books.
（該句改為 I like reading books或I'm interested in books) So I want to buy some interesting books.I like reading it.
(it改為them,不然文章前后不一致） But after an hour.I am very tired and thirsty.Then,I am sitting on the chair.Mum ask
（ask改為asked) me"What is the matter with you?" "I am very thirsty .I want some water." "Waht
(What) do you like?There is some water,some juice,some caffee and some tea on the table.What do you want?" "I want a bottle of juice.Because it is very sweet." So my mother is giving buy（?is giving buy怎么兩個動詞,直接用bought就好了） a bottle of juice for me.I am very happy.I am drinking the juice.
日記的時態(tài)應(yīng)該用一般過去式,文章時態(tài)錯誤.但小孩能寫成這樣已經(jīng)不錯了,句子整體的結(jié)構(gòu)都很完整.