A. three times B. three times like C. three times as D. three times larger
17. When you are in your room, leave the door ______ so that your visitors do not have to knock.
A. open B. opened C. opening D. being open
18. Earth is believed to ______ by an object the size of Mars at some point in the distant past before its surface cooled.
A. be hit B. have hit C. have been hit D. being hit
19. The only thing ______ really matters to the parents is how soon their children can return home.
A. what B. that C. which D. this
20. It is unacceptable that a person ______ for an uncommitted crime.
A. gets punishing B. punishes C. get punished D. punished