Essays / Essay on Reasonableness of Postal Rule [4]

Hello,guys!
I am a student from China and recently I'm going to hand on an essay "on reasonable of postal rule" in English .It almost makes me mad because I'm really poor in laws and I always find it difficult to translate the Chinese version into English.So I come to here and ask some help.

If any of you can offer me some relative information or references,I'd appreciate that very much!