恐怕我星期天之前赶不回来。
I'm afraid I won't be back before Sunday.
本句指星期天之前用将来时，not... until直到才。上述回答中用can't不妥。I'm doubtful I can come back before this Sunday.
I'm afraid I can not come back before Sunday.
I'm afaid I can't return before this Sunday.
I'afraid I can't be back until next monday.
I'm afraid I can't be back until next monday.
I think I won't be back until this sunday.
I am afraid i can not come back before Sunday.
Sorry， I am afraid that I couldn't back before Sunday.
为了表达委婉的语气，最好使用虚拟语气。
恐怕我星期天之前赶不回来。I'm afraid I can't rush back before Sunday.
这样就把那个"赶"字翻出来了.
建议你把前面的几种翻译总结起来。
I am afraid I can't/won't come back before Sunday.
Sorry,I am afraid I couldn't come back before Sunday.
再加上下面这一句：
I don't think I can come back before Sunday.就可以了。
中文的 "恐怕" 是婉若的说法, 正就是英文的 "I'm afraid".
两者和 "怕" "afraid" 是无关的.
doubtful 在这处不太合用.
用 can't come back (口语) / cannot come back (书面),
但不要用 can not. 是 cannot.
I'm afraid I can't come back before Sunday. 口语说法, 简单明白.
I'm afraid I can't come back before Sunday
I am afraid i can't come back before this sunday.
