mona promised that she .......... home tomorrow
(be - would have been - will have been - will be)
ليه الإجابة will be
مش would have been

I think because of promise

تم عديل هذة الجمله فى كتاب the best
Mona promised that she ......home the next day.
(be -will have been -would have been -would be)
وبالتلى طالما promised يبقى would+inf ومثل هذة الجملة فى كتاب الورك بوك
She promised she .would phone....... me as soon as the plane landed
اما لو مضارع نختار will +المصدر

Mona promised that she will be home tomorrow

الإجابة will be لان فيه promised / tomorrow