1. Volcanic __ grounded thousands of passengers and fliers across Europe last year. 


2. A:Did the committee members ask you many questions in your thesis defense? B: [   ]. I am not optimistic about the result of the defense.


3. He is a very conscientious professor. Never [   ] he let his students leave his classes earlier.


4. Jenny was brought up in a poor family. She had to [   ] her free time to baby-sit her neighbor’s 2-year-old boy to pay for her high school education.


5. The president’s reckless actions have [   ] his country into a disaster.


6. It’s a pity that I failed again. If I had read the book carefully,     the test. 


7. Sara felt [   ] tired [   ] exercise yesterday.


8. 《Tom》:I’m going to take a singing class. Do you want to take it with me? 《Penny》: [   ]《Tom》: Really? Sing a song for me now.


9. Parents with [   ] daughters and sons can bring up the problems they had with their 13 to 18 year-old children at the meeting next week.


10. A: What does 420 [   ] 100 equal? B: It equals 320.


11. The western coalition is trying to [   ] Libya’s air-defense system to protect civilians and help rebel forces.


12. The air traffic controller informs the pilot how far [   ] from the touchdown point.


13. Many buildings in Taiwan, including the Taipei 101 Tower, [   ] all non-essential lights from 8:30 p.m. to 9:30 p.m. yesterday to mark the worldwide “Earth Hour” event.


14. You could not [   ] all of your readings the night before the exam. You had better start to prepare for the test at least a week earlier.


15. In my [   ], students shouldn’t spend too much time chatting on the Internet.


16. Joy and happiness spread throughout the Middle East and North Africa, where people [   ] their own president in January 2011.


17. There is a risk that the longer people put off their work, __ it will eventually get done. 


18. After the car accident, I kept __ that things will get better. 


19. The National Palace Museum will continue to cooperate with Beijing's Palace Museum [   ] will not loan artifacts to China.


20. I sent an email to the CEO of this company last week but have not received any [   ] yet.


21. Las Vegas is a tourist [   ]. It's a must-go place for visitors who go to the U.S. for vacation.


22. The escaping criminal [   ] himself as an old security guard, so the police failed to recognize him at first sight.


23. I might have the chance to visit the theater [   ] person.


24. All of [   ] have joined the on-the-job training.


25. He didn’t want his wife to worry, so he was [   ] to tell her he didn’t feel well.


26. Tammy receives no payment because she is a [   ] worker in the hospital. She works there just because she enjoys helping people.


27. We have to admit that everyone of us is more or less __ to some sort of superstition. 


28. Snow [   ] more solar radiation than liquid water. Therefore, don’t forget to protect your eyes when you go skiing.


29. I am looking forward to [   ] from you at your earliest convenience.


30. Please fill out the paperwork before [   ] in line.


31. The congressmen have reached a ____ that smoking should be banned within thirty feet from the entrance of a building. 


32. I [   ] out a document when my boss walked into the office.


33. I remember you. You [   ] to go to school here.


34. Since Michael and I work in the same hospital, I can hardly avoid [   ] him.


35. Many companies [   ] e-mails sent out by their employees. Is it OK for employers to check on their employees like this?


36. Defined most broadly, folklore includes all the customs, beliefs, and traditions that people have [   ] from generation to generation.


37. A harmful chemical has been found in US beef products, so many [   ] choose to buy local beef instead.


38. This book offers a     guide to hotels in Tokyo. The author made a report on every single hotel there. 


39. Paul was charged with [   ] driving after he was arrested for running over an old man.


40. Shelly prefers red roses [   ] yellow ones.


41. Cheating in exams is a serious [   ] of the school regulations.


42. It was really a [   ] for the little boy to survive the air crash.


43. In this age of globalization, when people have more chances to travel, it is a great [   ] to speak more than one language.


44. A restaurant manager should know how to deal with [   ] from customers who are not satisfied with the food or the service.


45. I can’t ride my bicycle [   ] there isn’t any air in one of the tires.


46. [   ], I didn’t like Susie, but then I found she was a nice girl. Now we’re good friends.


47. This contract is __ approval by both parties involved. 


48. The search engine gives the user easy [   ] to the required information.


49. You should live within your income. Otherwise, you won’t be able to earn enough money to [   ].


50. A: Is the treasurer in his office every day? B:Oh yes. [   ] he must sign all checks, he must be here all the time.