16. They don’t find out the remedy. The patient will die.
=> If they found out the remedy, the patient wouln't die.
17. Susan felt sick because she ate 4 cream cakes.
=> If Susan had eaten 4 cream cakes, she wouldn't have felt sick.
18. If he hadn’t wasted too much time, he wouldn’t have failed in his examination. (Unless)
=> Unless he had wasted too much time he wuoldn't have failed in his examination.
19. Rita is exhausted today because she didn’t get any sleep last night.
=> If Rita wasn't exhausted today, she would have got some sleep last night.
20. The flats are not clearly numbered, so it is very difficult to find anyone.
=> If the flats were clearly numbered, it wouldn't be very difficult to find anyone.