Fill in the blank with a modal auxiliary showing certainty.
If computers are used in poorly lit places, users ____ suffer from headaches.
Must
Would
Ought
Will
If computers are used in poorly lit places, users will suffer from headaches.
I _______ have submitted the cheque to the bank in the morning.
Fill in the blank with a modal auxiliary showing possibility. She _____ be in the library, but I am not sure if she has your book.