4. Since many of our house plants are from humid jungle environments, they need _____ air to keep th
5. The skydiver managed to land safely after jumping out of the aircraft, even though her _____ fail
6. The invention of the steam engine, which was used to power heavy machines, brought about a _____c
7. To encourage classroom _____, the teacher divided the class into groups and asked them to solve a
8. Lisa _____ onto the ground and injured her ankle while she was playing basketball yesterday.(A) b
9. Hundreds of residents received free testing _____ from the city government to find out if their w
10. The 2011 Nobel Peace Prize was awarded _____ to three women for the efforts they made in fightin
11. The company is _____ and making great profits under the wise leadership of the chief executive o
12. It is absolutely _____ to waste your money on an expensive car when you cannot even get a driver
13. The problem of illegal drug use is very complex and cannot be traced to merely one _____ reason.