Which ones in the following are correct about the writing of application letters for jobs?
选项：

A:The only one purpose of the letter lies in proving that the applicant is qualified or excellent to take a certain job.
B:All the information in the letter should be closely related to the job objective.
C:The letter should be written no more than 1 piece of A4 paper with many short paragraphs in order to save the readers' time and energy.
D:If the applicant is excellent enough, it is unnecesary for him to show his respect to the readers(employers, HRs, etc.) in the letter.