تَظُنُّ أَن يُفْعَلَ بِهَا فَاقِرَةٌ
Ta th unnu an yufAAala bih a f a qira tun knowing that a crushing calamity is about to befall them.
 - Mohammad Asad
thinking that some backbreaking calamity is about to be inflicted on them.
 - Muhammad Farooq-i-Azam Malik
anticipating something devastating to befall them.
 - Mustafa Khattab
Thou wilt know that some great disaster is about to fall on them.
 - Marmaduke Pickthall
In the thought that some back-breaking calamity was about to be inflicted on them;
 - Abdullah Yusuf Ali