信件类英语作文万能句

I am writing this letter to express my sincere gratitude for your help.

I take great pleasure in thanking you for your kind support.

I am writing to apologize for not replying to your letter sooner.

I must apologize for any inconvenience caused by my mistake.

I would be delighted to have you join us for dinner.

Would you please consider accepting our invitation to the concert？

I'm writing to inquire about the availability of your services.