Read the passage and choose the best answer to each of the following questions.

There are many ways for dioxin, the toxic contaminant in Agent Orange, to enter the human body.

To estimate the number of Vietnamese who have been impacted by Agent Orange, it is necessary to separate the exposure into three modalities. First is the past direct exposure to the poison in wartime. Second are those who may have been exposed to dioxin during or immediately following wartime through the contaminated soil or consumption of contaminated fish and animals. Third are those who are currently being exposed to the dioxin contaminant that remains in the soil. In addition, there are those in the second and even third generations who were not directly exposed but are potentially being impacted due to their parent’s or grandparent’s exposure.

The population of South Viet Nam during the years of herbicide spraying was approximately 18 million. Jeanne stellman and her colleagues at Columbia University Mailman School of Public Health estimated that up to 4.5 million Vietnamese were living in the 3,181 villages that were directly in the spray paths and were potentially exposed to the dioxin. In addition, approximately a million more soldiers who were fighting in southern Viet Nam during the war were potentially exposed as they traveled through the sprayed areas.

Unfortunately, there are not any firm figures for the number of adults who suffer from or have already died from illnesses associated with exposure to Agent Orange. We also do not know for sure how many children and youth have disabilities that may be attributed to their parents’ or grandparents’ exposure to the herbicides.

(Excerpted from Agent Orange Record)

5. I haven’t visited my grandmother for 2 months (ago)

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4. He began to teach English for disabled children in 2002. (since)

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3.  This campaign has been launched since 1999. (for 20 years)

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2.  This is the first time I have visited Edinburgh, (never)

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5.  _________you ever_________in any voluntary work?

4. Last year, she_________students who wanted to play tennis.

3. Since I started working with children with disabilities, I_________kinder and more sympathetic.

2. I_________several extracurricular activities for children so far.

5. They (cancel) _________the meeting.

4. We (collect) _________more than a hundred gifts of all kinds in the past few weeks.

3. He (visit) _________the orphanage 3 times this week.

2. Up to the present, no decision (make) _________.

5. People’s attitudes towards the disabled changed.

4. Edison has developed hearing problems at an early age.

3. It was Louis Braille that has invented a system of reading and writing for use by the blind or visually impaired.

2. He lived with his grandparents since he was small.

27. I_________for this organisation since I_________from university.

D. have worked - have graduated

26. I have never told lies to you_________we became friends.

25. When I was 5 years old, I_________to church for the first time.

24. Everyone noticed that he_________to be sympathetic in the last meeting.

23. When I was a kid, I_________to share my bedroom with my sister, but now I need more privacy.

22. I know you are busy but you_________your homework yet?

21. He_________blood 3 times since he attended university.

20. My class visited a special school_________.

19. The little girl_________a thousand paper cranes so far.

18. I_________him 5 years ago at our friend’s wedding.

17. I don’t have enough time, so I_________my homework yet.

16. She_________four novels, and now she is writing the fifth one.

15. My sister_________home late last night after attending a night party.

14. The Youth Union in our school_________to launch a campaign to raise funds for the underprivileged.

13. International Day of Persons with disabilities_________since 1992.

12. Up to now, more than 80 countries_________on the Convention.

11. I first_________her when we were in secondary school.

10. Alice_________to work the day before yesterday.

9. He left the army in 1983 and_________as a guard in an orphanage.