Rearrange the words to make the complete sentences

Rearrange the words to make the complete sentences
1, 182 centimeters/ Dutch men now/ the study found that/ have an average height of/ more than
2. volunteers/ my classmates/ every Saturday morning/ Centre/ at the Happy Mind Charity.
3. by pro-Russian separatists/ when flight MH17 crashed/ nearly 300 people/ in territory controlled/ were killed
4. in our area?/ what is/ the most important/ activity/ volunteer