阅读下面的短文，在空白处填入一个适当的词，或填入括号中所给词的适当形式。
I have two good friends. They are Mike and Jim. We study in the same school but in different. They are very helpful and friendly. They both give away several hours each week(help) others.
Mike likes animals very much. His favorite animals are pandas. He also likes dogs and cats very much. He wants(be) an animal doctor when he(grow) up. So he volunteers at an animal hospital every Sunday. He thinks the work can help him to get his dream job. He can learn a lothow to care for animals. He can get a strong(feel) of satisfaction when he sees the animals get better and the look of joy on their(owner) faces.
Jim likes singing. He practices singing in the morning every day. He often goes to the primary school to teach the(children) to sing. He can also play the violin well. Some children want to learn to play the violin. So Jim usually teaches them to play the violin on weekends. He thinks(volunteer) is a dream which has come true for himhe can do what he loves to do and help others at the same time.