15. She would have passed the exam if she had studied hard
16. The children insisted on me staying with them
17. Though he has been studying for many years, he should have realized sooner that his grammar was incorrect
18. Colour, an important facet of nature, influences the life of almost every creature
19. She applied for the abroad in order to develop herself and earn more money
20. No sooner had the teacher appeared than all the students kept silent.
