That is joke

When a person tells you about something you don't know, you say that 'I don't know' truthfully. That one thinks that is a your joke answer only. What should I say to make you believe me?

(Khi nguoi nao do noi voi nhung vai dieu ban khong biet, ban thanh that tra loi ' Toi khong biet'. Nguoi do nghi do chi la cau noi dua cua ban. Toi nen noi gi de ban tin toi?)

My noble boy

There was a boy who is very kind.he went out in the morning ,the sun is shining and the birds are singing, that day is very beautiful .he feel like happy in his mind .at the time unexpectedly ,He saw a old woman .the old woman seen to some problem ,because she need to buy some food .but she has not enough money .so she checked her money in her pocket money again and again .but she didn't seem to have enough money .so she was so sad
the noble boy seen all about that women .the noble boy came near to the old woman .After the boy asked her politely ,what happen grandmother ?what can I do for you ?the old woman look him .she speak slowly my son I need to buy some food .but my son I have not enough money ,so I am very sorry .the noble boy reply to the old woman ,don't worry about that I can solve your problem .the noble boy some giving buy food for the old woman .the boy asked the old woman ,Grandmother ,where are you going now?The old woman said I will go hone.I will take to your home .Thank a lot my son I will never forget your help.your very kindness your good boy.