在英语作文中，表达期待回信的情感时，可以使用以下几种常用的万能句子：

Wehopetoreceiveyourfavouratanearlydate.

Wehopetobefavourwithareplywiththeleastdelay.

I look forward to your reply.

Please write back soon.

Take good care of yourself and write often.

I hope to hear from you soon.

Looking forward to your reply.

I am looking forward to receiving your letter.

Time past cannot be called back again.

Lookforwardtoyoursoonestreply.Pleasewritebacktomeassoonaspossible.

这些句子可以根据具体的语境和需要进行选择和使用，以确保表达清晰、礼貌且符合英语写作的习惯。