A person’s life may never be separated from a number of certificates. For example, when you are born, you have a birth certificate, when you grow up, you have an identity card, when you graduated from your school, you have a graduated certificate, a grade certificate, or certificates of other skill ,when you are in love until marrage, you have a marrage certificate, when you are engaged in a special work, you need a employee’s certificate card, when you go aboard, you should show your passport and visa.