1. Raising funds for poor children is one thing you may do. (MIGHT)
Raising funds might be  one thing you do  for poor children
2. She doesn't join any volunteer activities. She says she is busy. (BECAUSE)
 She doesn't join any volunteer activities because she is busy.
3. My school may hold some volunteer activities. I am thinking about joining the animal care project. (IF)
if my school hold some volunteer activities , i will join he animal care project.
4. My parents often go to villages to do charity work. I go with them. (AND)
My parents and me often go to villages to do charity work.