Drugs are tested in patient volunteers to monitor adverse reactions to long-term use.

A. After Angelina Jolie began taking an interest in charity work, she was filming in Cambodia.

B. Angelina Jolie began taking an interest in charity work while she was filming in Cambodia.

C. Before Angelina Jolie was filming in Cambodia, she began to take an interest in charity work.

D. As soon as Angelina Jolie began taking an interest in charity work, she was filming in Cambodia then.

A. Some students took part in directing the traffic, so some others took care of the war invalids.

B. Some students took part in directing the traffic, for some others took care of the to war invalids.

C. Some students took part in directing the traffic, and some others took care of the war invalids.

D. Some students took part in directing the traffic, but some others took care of the war invalids.

A. If SHARE is a non-profit organisation, it will provide thousands of girls in Africa with books and school supplies.

B. Although SHARE is a non-profit organisation, it provides thousands of girls in Africa with books and school supplies.

C. SHARE is a non-profit organisation until it provides thousands of girls in Africa with books and school supplies.

D. SHARE is a non-profit organisation which provides thousands of girls in Africa with books and school supplies.

A. They were busy with their schoolwork, but they still spent time helping the elderly in the retirement home.

B. They spent time helping the elderly in the retirement home, so they were busy with their schoolwork.

C. They were busy with their schoolwork, and they spent time helping the elderly in the retirement home.

D. They spent time helping the elderly in the retirement home, or they were busy with their schoolwork.

A. Despite his young age, the boy established an athletic programme for children with special needs.

B. Until the boy was only 10 years old, he established an athletic programme for children with special needs.

C. The boy established an athletic programme for children with special needs because he was only 10 years old.

D. The boy established an athletic programme for children with special needs in case of his young age.

A. There exists no single solution to solve all communities' problems.

B. Not communities share the same problems, hence no single solution.

C. All communities have their own needs but require the same solution.

D. There is no one solution to meet the needs of all communities.

A. The education itself has been considerably impacted by volunteering activities.

B. The impact of volunteering on the education system itself is worth considering.

C. There is a considerable impact of volunteering on its education system itself.

D. It is the volunteering activities that have considerable impact on education.