Fear is one of the many enemies hidden inside us, and if ____ uncontrolled, it can destroy our lives.
A. living
B. left
C. having left
D. to be left
She is always thinking more of herself, seldom, ____, offering to help others.
A. if never
B. it's possible
C. if ever
D. if any
The flowers he bought will die unless ____ everyday.
A. watered
B. watering
C. being watered
D. to water
If ____ in class, you will have to clean the classroom for a week as a punishment.
A. to catch to sleep
B. caught to sleep
C. catching sleeping
D. caught sleeping