Dear Yang Kai,
Would you like to go out for a picnic with my brother and me at 3: 30 on Sunday afternoon?
We will have the picnic in Yingze Park. You know where it is, don't you? You can take the No. 6 bus to the park. After you go into the park, walk straight on for about five minutes until you come to a small but clean river. There is a bridge over it. Go across the bridge and turn left. After walking for ten minutes, you will come to a hill. Walk to the other side (边) of the hill and you will see a lake (湖). We will have the picnic by the lake.
I'm sure you will find us easily. Don't forget (忘记) the time.
Yours,
Hao Gang