英语的求职信

Dear sir,
Four years as a senior clerk in sales department of the New World Products Company have,I believe,given me the experience to qualify for the job you advertised in Thursday's newspaper.
Since 1981 I have been responsible for all office details in the administration of sales,including writing much of the correspondence.In the course of my work,I have become familiar with the various sales territories,and have also in my spare time experience of handling business problems other than my proper sphere.
The years before I was employed at the New World,I was a secretary for Long Brother,an accounting firm.There I became familiar with accounting terms and procedures.
I was graduated at Wah Yan College, in June 1974. I am twenty-five years of age and single.
I am leaving my present position because I can use my capabilities more fully in a position with wider scope. My present employer knows of my ambition and is helping me to find a new place.
May