推迟日期英语

I would like to ask whether I can postpone the deadline of ....比较正式而且客气.

1. I am writing to ask if it is possible that I could do/finish/submit...... until....(时间)。不直接说明“推迟”，只表示能在什么时间完成（间接表示推迟）。2. I am writing to ask if it is possible that I could postpone ....(直接说出要推迟，如一楼所说~)ps 我个人常用 “i am writing to ask if it is possible that……"，觉得比较礼貌正式。

Set sail postponed until the Spring Festival period of English how to say

Sailing date delay to during the Spring Festival

dear prof. **,i am so sorry for not being able to finish my thesis because of my disease, and i hope you could allow me to postpone it for several days.many thanks.