One day, there was a young Mum took her two sons come to visit our garden. The two sons sat in a large trolley（手推车） and by the marine fish tanks.

The two boys were about 4 or 5 years old and looked like copies. I asked the young lady:

"They are your sons?"

"Yes!" She was very happy and with a pride.

"They are twins?"

"Yes!" She still kept good feeling.

A few minutes' quiet.

"There are twins, why the eyes are different. One is black as me, other one is blue as you" I want make a joke and asked.

"I know! But I don’t know why!" She answered me with the smiling faces.

The two boys looked at me strangely.