by 有多种说法：a merry day.a happy day，a nice day，a pleasant day……
如：
Today is a happy day. 今天是开心的一天
It's a sunny day ，the bird is singing.When I get to park，I see some friends are playing games ，so I join them.We play very happy.Then I have lunch with my friends.We both have a good time.what a happy day it is!
今天是一个晴天，小鸟们在歌唱。当我到达公园的时候，我看到一些小朋友正在玩游戏，所以我加入了他们。我们玩得高兴。我和他们一起吃午饭。我们度过了美好的时光。今天多快乐啊！