结构：
Part1: Among various kinds of things/persons in my mind, …is the most unforgettable one.
Part2: On a sunny/rainy morning, while I was …First of all… Then…  After that…In the end… 
Part3: he/she/this was one of the most meaningful/enjoyable/unforgettable persons/things that I have ever met/experienced, I will remember him/in forever.
加分句子：
Sth impressed me greatly
What impressed me most is that…
I admire Helen because she is optimistic about life.
Developa better relationship between each other.
Before leaving we took some photos to record our green action. Seeing the lines of trees, we all had a sense of achievement. We feel it’s our duty to protect and beautify our environment.